[2022] Starting 3 ending up solo, does the game adept to solo player the next sub zones?

When my both teammates die in the 2nd Zone. I complete the mission in this 2nd zone, evac them and be able to move forward to the third zone. Is it better to evac or can I do the 3rd zone solo, because the game changes the 3rd Zone to Solo environement, cuz I'm on my own?

Also if a player disconnects, does it adept? or is it safer to evac in this case...