God I wish chrome didn't remove manifest v2 
Here is the list of things that piss me off about firefox:
- It is dogshit slow
- It eats up a ludicrous amounts of RAM, which I wasn't expecting since it's one of the main things people make fun of chrome for
- It crashes constantly
- It tries to push it's "AI" bullshit on me despite me turning it off on multiple occasions
- It puts ads on my home page
- It needs to be relaunched regularly because at some point it becomes too laggy to use. It even stops loading pages altogether
- "Restore previous session" feature doesn't work half the time so restarting the browser is absolutely terrifying
- Profile management is a mess
Are there any alternatives? Is Brave any good?
I've never had any of these problems even on stock Firefox.
Try Librewolf. It's a Firefox fork with sensible defaults (ad blocker preinstalled, telemetry disabled, some privacy settings enabled by default, no AI bullshit).
Some of the things you describe are definitely bugs you should be reporting to Mozilla. The crashes, memory usage, slowness, etc. I don't experience them and they sound unusual to me.
I'm gonna be honest—it sounds like you're using the feature for things it's not intended for. If you want to save pages to go back to, you should use bookmarks. I only use "restore previous session" upon crashes or when I restart my browser due to an update, and it works fine for those use cases.
Hell yeah for "no AI bullshit"!
I think they are aware of it because it's gotten a bit better since the last update.
I use it exactly the same. My problem is that it doesn't always restore all the windows that have been closed. Apparently it's a known issue because I found some janky workarounds online
Ah fair enough, in that case I can only recommend you try Librewolf and see if you have the same problems because I don't experience them. Most people I know use either Firefox or a fork and I haven't heard of these problems so it at least doesn't sound normal to me.