Icons not showing properly

Hi!
I’m having some issues with most of the icons on my website. They does not show the way they should. For instance, at the home page you can see the icons on the left of each word (“simple”, “versatile”…) (screenshot 1) , on the search box (magnifier doesn’t show and one can’t distinguish it) (screenshot 2) , at the social icons at the left side on the pre-footer (screenshot 3) , or at the “scroll to top” button on the bottom right side.

I started editing this website on a Windows PC and then resumed the job on a Mac using Safari. The thing is this issue does not appear when displayed on Safari or through Apple’s iPhones. It’s just a matter going through Chrome, Firefox, Edge, Android…
When I try to edit the home icons, for instance, I get this weird icons (screenshot 4) and I’m afraid it’s something related to fonts… I really don’t know what can solve it and why it works just through Safari.

Help would be really appreciated.

Thanks in advance.