Slider/portfolio grid not working after upgrading WordPress to 5.6.1

Hi there,

After a recent update of WordPress, the sliders on my website is not working. Only blank spaces are shown there. The portfolio grid is not working as well. The menu humbuger on phone is not working as well.

I tried to downgrate jQuery to 1.12.4, but not working well. All the plug-ins are disabled except jQuery Migrate.

Here are some images to show the current situation.

https://imgur.com/rB7I1py the slider on the home page cannot be loaded.
on page https://nanjiangames.com/games/, the product portfolio can not be loaded. https://imgur.com/8hlpqd1

The admin login information is provided in the private content.

Please help with the issue.

P.s this post is a repost from https://kriesi.at/support/topic/slider-portfolio-grid-not-working-after-upgrading-wordpress-to-5-6-1/#post-1279173