AVIFs are better for most sites to because they are smaller, got better compression rates than PNG, and look a hell of a lot better than JPG. They also turn a bit sour when you pull them from sites to have on your desktop. Sites that don't like people downloading their images and shit love this about AVIF most. WEBPs are just as nice(shit).
Honey Select, Honey Select2, AI Girl, etc all use metadata embedded PNG files to allow sharing of created characters. The size of her nose, the girth of his pecker, what hair mod you chose is all slider metadata embedded in the PNG file. In having a character sharing vehicle this way, you not only can easily share girls with your friends and fellows, you can always see a basic idea of what the girl/guy looks like.
Any site you post/share a Honey Select 1-2-AIG character card that translates it to AVIF, it's destroyed. The game can't read the meta-data anymore because that was part of what the AVIF auto-converter removed for the sake of smaller filesize.
The solution is to post game character cards you make in a 7zip, rar, or zip archive. This will keep them safe
and shareable for years to come.