Have it mandatory to use private servers for hosting trainings
Why?
Players have 500+ ping even without trainings happening in the server, and it simply ruins the whole experience of playing the game because player count gets over 80 (so the ping is probably more than 1000 which is barely playable) when there are trainings happening.
Someone might say "but no one will be in the main server then!"
Okay, and? The server might be full but players will have 1k+ ping and half of them are in the training so WHAT IS THE POINT?
It gives freedom to raiders
They can freely terminate anyone without being afraid they might be in the training.