first – maybe you decide not to have this immense padding of 100px of that cell – because expanding the content will end in a very hight container.
next: set for the background-image position : bottom center.
put this to your quick css and adjust to your needs:

#top .av-fold-unfold-container.unfolded {
  background-color: rgba(0,0,0,0.3);
  border-radius: 15px;
  padding: 10px;
  -webkit-backdrop-filter: blur(3px);
  backdrop-filter: blur(3px);
}

if you like to have a semi-transparent white bg – change to rgba(255,255,255,0.6)
but then i would change font color to f.e. #333

#top .av-fold-unfold-container.unfolded p {
  color: #333;
}

i have installed contact form 7 to nearly all of my enfold installs. They do not load Google Fonts at all. Do you use f.e. google recaptcha in contact forms?
Google Recaptcha is loading extra google fonts (f.e. Roboto or Google Sans.

well – remove that second color section and put this to your quick css:

#top.page-id-238 #av_section_1 { 
  background-image: url(https://substratosfera.it/wp-content/uploads/2024/12/substrato_separatore.png), url(https://substratosfera.it/wp-content/uploads/2024/12/substrato_background_top-1.png);
  background-repeat: no-repeat;
  background-position: bottom left, 100% 0%;
  background-size: 130%, contain;
  background-attachment: scroll, fixed;
}

but : if i look to your logo – it might be a good idea to transform the upper part and the lower part as svg to a custom divider ;)
do you have your logo as verctor based file? – post a link please

or try instead:

#top.home #av-layout-grid-1 fieldset {
  display: flex;
  flex-flow: row wrap;
  justify-content: center;
  gap: 5px;
}

#top.home #av-layout-grid-1 fieldset p {
  width: unset;
}

#top.home #av-layout-grid-1 fieldset p:first-of-type {
  width: 50%
}

#top.home #av-layout-grid-1 fieldset p:first-of-type input {
  border: 1px solid #be363c;
  border-radius: 26px 0 0 26px
}

#top.home #av-layout-grid-1 fieldset p .button {
  border-radius: 0 26px 26px 0;
}

and maybe you style that black box a bit too : change background-color and add some css :

.custom-black-box {
  background-color: rgba(0,0,0,0.3);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
}

i did not compare both css rules , but you should know:
If there are two or more CSS rules that point to the same element, the selector with the highest specificity will “win”, and its style declaration will be applied to that HTML element. Every CSS selector has a position in the specificity hierarchy.

the #top selector has a high hierarchy – so that rule wins – and even by this – the ID wins.

Unfortunately, it is becoming more and more common to set a porperty value to !important in order to enforce a css rule. In many cases, it would only be necessary to adapt the selectors better.

as participant – i do not see your page – so hope Mike has a good idea. But keep in mind: better to place them fixed and to position them all top left.

And you only trust Mods ?

function ava_g_tag_custom_script() { 
?>
<!-- Google Tag Manager -->
<script>
  (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
  new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
  j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
  'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);
  })(window,document,'script','dataLayer','GTM-XXXXX');
</script>
<!-- End Google Tag Manager -->  

<!-- Google Tag Manager (noscript) -->
<noscript>
  <iframe src="https://www.googletagmanager.com/ns.html?id=GTM-XXXXX"
  height="0" width="0" style="display:none;visibility:hidden"></iframe>
</noscript>
<!-- End Google Tag Manager (noscript) --> 
<?php
}
add_action('wp_head', 'ava_g_tag_custom_script');

the reason why this fails – is that a lot of participants do not use the code tag on posting snippets here : https://kriesi.at/support/topic/adding-google-tag-manager-in-enfold/#post-1473588

can you test if the setting on : SEO Support – Search Engine Optimization Support – Meta Tag “robots” : Use Enfold default settings.
clear cache and merging and look if it is still there. If not then your SEO external Plugin is causing it.

The new robots tag, indexifembedded, works in combination with the noindex tag only when the page with noindex is embedded into another page through an iframe or similar HTML tag, like object. For example, if podcast.host.example/playpage?podcast=12345 has both the noindex and indexifembedded tag, it means Google can embed the content hosted on that page in recipe.site.example/my-recipes.html during indexing.

But as menitioned above – i do not have that on any enfold page. This is something that might come from a plugin.
the one and only place where Enfold places a noindex is in function-set-avia-frontend.php lines 466ff in the function: function avia_set_follow()
and this is just for the <meta name=”robots” …/> for is_search

a indexifembedded is completely not found in enfold folder ! if this setting comes from enfold it has to be mentioned in the source code.

Can you test please:

put this to your child-theme functions.php:

add_theme_support('avia_show_alb_responsive_image_option');

after that open your masonry element and look to advanced tab – performance : do not use responsive images.
This i hope will end in showing the original image instead of the smaller calculated images.

On styling tab choose (just for testing purposes) “no scaling (original width…)” now see if the uploaded images are yellowish too.
If not then there went something wrong on recalculating the smaller (for responsive purpos) image formats.

maybe put this to child-theme functions.php to show original images in lightbox:

function custom_alb_lightbox_image_size( $size, $context ){
  if( $context == ('av_gallery' || 'avia_masonry') ){
    return 'original';
  }
  return $size;
}
add_filter( 'avf_alb_lightbox_image_size', 'custom_alb_lightbox_image_size', 10, 2 );

If this shows now in masonry and on lightbox the well saturated images – then you can use once the plugin : https://wordpress.org/plugins/force-regenerate-thumbnails/ and recalculate all images. This i hope will correct the mismatch. After recalculation you can delete that plugiin from your installation.

did you really read my post and followed the link i offered?

@mike – it is as mentioned just before head tag is closing. But i do not have it on any of my enfold installations even on those which are in combination with Yoast SEO.

but nevertheless in combination with that “new” indexifembedded it is ok :
https://developers.google.com/search/blog/2022/01/robots-meta-tag-indexifembedded

nice to see the page now – then it is much easier to give advice.
First – why do you use the image as background? – use it as image element inside that column.
Best would be to give a custom class to that flex-column with your image.

to see an interims result – that could be done:

@media only screen and (min-width: 768px) {
  .flex_column.av-cvo-a82f70a62f8490e3b0b75af0c90996f9 {
    position: absolute;
    bottom: 0
  }
}

But: i guess we can have better results if you do not use the equal height option! because in responsive case the height of those containers are too big.
So can you please give to the flex-column with that image a custom class and remove the equal height option – then i check if there is a better solution for every screen width.

See example with css code : https://webers-testseite.de/greg/

i guess – as the frames – it will be better for positioning to choose display : fixed
I don’t know how the vw unit reacts to the scroll bar thickness. However, it seems to be the case that this must unfortunately be taken into account. For this reason alone, it is important to align all four pseudo containers to the top left.
for the mentioned Demo this works in all browser i do have on my Mac (FF dev, FF, Safari, Chrome)

.av-frame:before,
.av-frame:after {
    pointer-events: none;
    display:block !important;
}

.av-frame.av-frame-top.av-frame-vert:before {
    content: '';
    left: 30px;
    top: 30px;
    height: calc(50vh - 30px);
    width: calc(50vw - 38px);
    border-top: 1px solid #102f5d !important;
    border-left: 1px solid #102f5d !important;
    position: fixed;
}
.av-frame.av-frame-right.av-frame-hor:before {
    content: '';
    left: calc(50vw - 8px);
    top: 30px;
    height: calc(50vh - 30px);
    width: calc(50vw - 38px);
    border-right: 1px solid #102f5d !important;
    border-top: 1px solid #102f5d !important;
    position: fixed;
}
.av-frame.av-frame-bottom.av-frame-vert:before {
    content: '';
    left: calc(50vw - 8px);
    top: 50vh;
    height: calc(50vh - 30px);
    width: calc(50vw - 38px);
    border-right: 1px solid #102f5d !important;
    border-bottom: 1px solid #102f5d !important;
    position: fixed;
}
.av-frame.av-frame-left.av-frame-hor:before {
    content: '';
    left: 30px;
    top: 50vh;
    height: calc(50vh - 30px);
    width: calc(50vw - 38px);
    border-left: 1px solid #102f5d !important;
    border-bottom: 1px solid #102f5d !important;
    position: fixed;
}

if you got a different frame width than 10px we had to adjust some settings.