Read some details in the issue and you will get an idea why they haven't migrated yet The size of the issues in their repo is huge! Especially when including media like photos and videos.

Also funding hosting for such a thing is challenging, AFAIK they found a Chinese sponsor, but some of the community weren't so pleased with them.

You don't have to archive every last media and binary file. The size will only increase as time goes on, and so too will the expense of maintaining the archive. Better to start chewing now rather than wait for Microsoft to finish off GitLab and look for other competitors to demolish. I think they will be quick to realize they have one playing around in their front yard.

But then right below that on the Gitea page you linked they list their docker pulls statistics, which is primarily the self hosted community. Mixed messages indeed