Sodium Plus
If you have any issues and you have used your launcher to update the modpack, try instead to make a new instance and see if that works.
If this works I am more than happy to help you transfer your data over on discord. If it still has some problem, create a github issue.
About
Sodium Plus aims to re-create the experience of the OptiFine mod, while still having the most resource-efficient Minecraft client you can have. It also comes with some visual tweaks, quality-of-life changes, and a couple of bug patches. A couple of these mods you may not like, as it changes gameplay, even if it is only client-side. Because of this, I might make a fair play edition later on.
Please submit any bugs or feature requests on out GitHub issues page: https://github.com/happyredstone/sodiumplus/issues
You shouldn't get banned or kicked for joining a current version of the game, but might have issues with older versions due to use of viaFabricPlus. I am not responsible for any bans you might get!
Server
Sodium Plus supports being installed on a server as of version 2.4.7. Install the SERVER release on the server, and the same number version on any clients. SERVER releases should work on clients, but there is no reason not to use the normal releases.