You can use a low strength product Loctite ( I think it has blue lid) to stop your motor screws and the others coming loose. Good job for a rainy day.
As for the twitching at full throttle, it could be many things, a throttle gimbal issue with your transmitter, an adjustment with your PID settings in Betaflight or one of your motors not spinning up the same as the other three. With that you would have issues everywhere when flying at nearly any throttle so hopefully not. I’m at work and nowhere near my computer to check what my PID settings are but a search on YouTube/google may have some tips.
All your props are in good shape, not bent slightly?
Has it only just started after a crash?
