MacBook Pro mid 2012 keyboard issue
It has nothing to do with your build in keyboard. What u have encounter is due to MacOs Catalina. I have same problem. It started from bottom row of alphabetic of your keyboard. You get multiple Z after pressing the Z button once until you have to press the return key to stop it. It sorts of like a virus escalated to the rest of your buttons on the keyboard. Slowly all your small caps alphabetic auto Caps Lock although you have not activated the Caps Lock and numerics auto change to symbols without pressing shift button. The WORST OF ALL COMMAND button + R button (have been remove from your drive) after the update to MacOs Catalina that does not allow u to access to internet recovery utilities. Further Damage done by Catalina is that many apps not be able to support. So congrates! All u could do is to restart your macbook pro whenever should these problem arise each time.