This would let banned players servers with online-mode=false. You won't be able to access servers that have online-mode=true, but at least you can play with your friends.

The Realms button would stay grayed out, since it wouldn't work properly anyway.

Could this be augmented to allow accounts that are unable to play multiplayer due to having the age set too young? I have a spare account that I bought for my brother, who is currently 11. I made the mistake of listing his real age in the account creation process, which caused the account to be unable to play multiplayer in post-1.18 versions. I ended up buying him a second account with a false age so he could play multiplayer with me, but I still have the original account lying around.

This. I've been told to get lost by Microsoft when spending my own money because my account is restricted.

Could this be augmented to allow accounts that are unable to play multiplayer due to having the age set too young?

Why not.

I'd appreciate some options for both, as I don't really want to condone offline mode server usage or ban circumvention overall in my modpack.

Edit: I saw that there is one option, does it work identically for both cases?

Edit: I saw that there is one option, does it work identically for both cases?

Yes. Why would that not be enough?

Oh, then indeed one option is fine. I thought underage players could've still joined online-mode servers with a workaround.

Was added in 1.19.1-pre2-v1.3.0.

This is already implemented in a76167b, I just need to actually release for 1.19.1, which is yet to drop.