I've been working professionally as a software engineer for a bit over 20 years, and I was programming as a hobby for over a decade before that. Been in a number of different industries; you can find interesting problems to work on anywhere, but life for a programmer is always best at a company whose primary business is software.
I think it's because of the server overload some instances have been suffering. It might be affecting sync between instances in addition to the timeouts for user interaction.
I'm on kbin, and to sub to a community on a lemmy instance, I have to replace the ! with a @, because that's the actual underlying name, it seems. It's a bit confusing.
The protocol they have in common is ActivityPub, the same thing used by Mastodon, Calckey, etc..