When I try to open Minecraft I have to sign in every time and when I open Minecraft and try to get on a server, it doesn't work because it signs me out right after Minecraft opens. I am using lunar client but I am using forge mods for another thing but I can't get on servers because of that. 

On the Affects Version/s, it is on 1.8.9 but I can't put it there so I just put 1.16.5 but the problem is also for 1.16.5 too and I tried it on 1.16.5, not modded, and it didn't work so stop saying invalid.