When leaving during multiplayer, it didn’t matter who was hosting, we’d be stuck in an infinite loading screen loop if both of us tried to leave at the same time or if the host left while the other was still disconnecting.
My friend didn’t have as big an issue with it as he had 2 monitors to work with, but I was on a laptop so only single monitor users experience this detrimental bug to its extreme.
Ctrl+Alt+Del to task manager didn’t work - Borderlands 3 was always on top. I couldn’t get to desktop, couldn’t Alt+Tab of course, Alt+F4 didn’t work. The only remedy for me was to force shutdown my laptop and restart.