Wait you mean when you are using slower Internet connection it allows to join the server and when you switch back to normal connection it starts to freeze?

Same thing happening to me with xbox normal an cloud play on some modded community servers. I suspect it caused by incorrect mods, like syntax errors in modded xml and json files. E.g. I tried on my nitrado server I purchased for tests and was kind of able to recreate issue when trying custom load outs by using example from bohemia site to ad AK load out. When using it my char would experience these issues and only server wipe would restore proper functionality.