A) long passwords: if you signed up for Lemmy with a password that's more than 60 characters, the lemmy UI silently truncated it to 60 characters without telling you. When you login via a browser, it also truncates your password, so it still works. However, Jerboa does not truncate the password, so you can't login with what you think is the right password.
Immediate personal fix is to change your password to something between 10 and 60 characters.
the lemmy devs are aware that silently changing people's passwords isn't ideal and are discussing what the right change is.
B) Occasionally I have to force stop the Jerboa app, clear all of it's saved data and re login to fix it's quirks. Super annoying but doesn't happen too often, so... 🤷
Everything is struggling due to the Reddit influx. The closer you are to the top of lists like awesome-lemmy-instances the more you're getting crushed right now. Also means already strugglling instances are going to struggle even more.
Think of instances as "continents" where communities (think of them as "countries") and users set up their base. For example, you're now in the lemmy.world instance. That means you are a resident of the lemmy.world instance.
You can "travel" to other instances and participate in the communities they have there too and vice versa.