This problem is not related to the photos app nor ios14! But it's related to the web browser. Chrome (and other browsers like opera torch, edge, Firefox, brave and...) had this annoying problem even in earlier iOS version (ios13). Safari was ok in iOS 13 but in ios14 besides of can't save animated GIF, it has performance issues when you view or save a GIF.
And in this situation, the solution is to use Maxthon or Aloha Web browser.
SiNNzRi
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution