Maybe you should ask your admin in !meta or !chat what’s up with the specific errors on your instance. Maybe they had some problems operating it. You can always switch instances. My posts never disappear without reason. (They can also be removed if they violate the terms of an instance or community.)
The other issues also annoy me. Federation is somewhat broken and posts and comments often don’t propagate to other instances since Lemmy version 0.19.0 (and 0.19.1 which should have fixed that.) It’s the fault of the Lemmy developers to release a broken update. We’ll see if they continue doing that or if they have learned something. I think they want to hire a third full-time developer. Maybe that helps.
The need to re-login and unable to login with an older client happened once. Things like that can happen if bigger changes are made. I don’t think this will become a regular thing. And it’s not that annoying in my eyes. Most importantly clients have to handle that correctly and give a meaningful error message and guide you to the login page. But some proper error handling is also missing here.
So: Yes. The things you mentioned also annoy me. Lemmy has still lots of room for improvement. And it’s nowhere near other federated platforms. I hope the Lemmy devs aren’t repeating the most annoying mistakes and fix federation soon so this can be an issue of the past…
Are you not annoyed by Lemmy's constant glitches?
On the instance I’m using, my comments and posts have disappeared. It is ok?...