Car vibrates while in drive and say "transmission service urgent" or something along those lines,

I've dealt with this problem of vibration before but now a lot more issues
are arising. I replaced all spark plugs and even got new ignitions coils but
that didn't resolve anything. When i'm on park and the lights inside the car
are on, they dim and brighten often.
What could cause this?
What do you think the fix could be?

Thanks for looking!