Not really, you can disable online mode and make your own authentication system (or use a plugin someone else made to handle authentication directly on your server). This is usually done to let non-premium (aka pirate) users join (which is, to my knowledge, against the Minecraft EULA), but I’m sure if Microsoft were to really mess up and do something like disabling multiplayer support for older versions (“pre-enshittification versions are not supported by our servers” or some bs), people would just authenticate it themselves, or make their own server software (challenging task but not impossible).
Not really, you can disable online mode and make your own authentication system (or use a plugin someone else made to handle authentication directly on your server). This is usually done to let non-premium (aka pirate) users join (which is, to my knowledge, against the Minecraft EULA), but I’m sure if Microsoft were to really mess up and do something like disabling multiplayer support for older versions (“pre-enshittification versions are not supported by our servers” or some bs), people would just authenticate it themselves, or make their own server software (challenging task but not impossible).