I'm not sure about chat, but mail was moved to a separate addon. The site admin can turn it on under Admin -> Addons - > Mail. It can then be installed for each channel owner.
Each time I click I need to wait.
You try an open instance then ... ohhh it miss activitypub or ..
Can an instance disappear without prior notification to its users?
That is, is this kind of behavior allowed?? I've never seen anything like this anywhere.
Where are my files, my posts, etc? How can I recover all that, with those instances gone?
if you know how to fix those problems, please expose it