This may not be a tips and tricks, but to share what we found.
When we uploaded GIF file image through AppSheet app, more precisely, upload GIF from Image type column, it becomes static images, not a GIF actually. In the past, we hosted GIF image file elsewhere and used the public URL to display the GIF image within the app, but we found the GIF files saved from AppSheet app and saved to the cloud is actually rendered as GIF. Good.
This GIF was saved / uloaded from Image type field.
By the way, for people who are learning about gifs in AppSheet for the first time, I recommend looking at this:
I followed up with this as a workaround for how to deal with the problem of gif animation stopping because it is used in more than one spot in your app:
For gif files that the creator wants to make part of the documentation in the app (to illustrate things for users), I suspect that the old method (putting stuff up on Google drive) may still be best. It is great to know, however, that ordinary gifs can be uploaded by users and that they will work.
By the way, I learned almost everything I know about gifs in AppSheet from @tsuji_koichi . I added a couple of little observations and clarifications in posts I made that followed up on his but he got everything started. Thanks Koichi!