What I did was made a 1.21 mod profile and copied all my mods over, it basically errored saying a few mods were incompatible so I removed those. After I did that, the game started up just fine but then crashed when I went into anything.
As much as I understand that, most servers are just going to tell you if you have any problems with older versions, just update. And I wasn't trying to be rude but if you would have read my post, you wouldn't noticed I said no 1.21+ servers
