After upgrading to Big Sur on my MacBook there are problems connecting to a Linux box it the Linux box has a default shell other than bash. If it has zsh or fish for example you get multiple errors complaining about the LOCALE variables not being set properly. If the box is using bash you can connect and then switch to another shell with no problem.
This just started when I upgraded from Catalina to Big Sur. No problems if I SSH from my Mac Mini which is still running Mojave, so it definitely appears to be due to some change in Big Sur.
Has anyone else seen this? My web searches haven’t turned up anything.