it might be that folks are adding the filter to the img {} CSS tag, and then removing all of it in img:hover {} in their css! there's also built-in CSS filters: https://www.w3schools.com/cssref/css3_pr_filter.php you can also search for "image hover effects CSS" and see if you can play with it!! :) i hope this was helpful!
going to make the biggest update ever!!! mostly it's just cosmetics but also... something else :)
thank you so much!!!