text pasting while typing on macbook pro

I am pretty sure this is due to the touch bar that is just above the top row of numbers on your Macbook Pro keyboard. If your finger(s) get close enough, it can be triggered, even if not actually touched! On my older work Macbook Pro, I had to reconfigure it to prevent this. For instance, when typing in Word, I see something on the far left of the touch bar that looks like a clipboard. It can cause a paste if it is either touched or if the finger comes close enough that it is sensed (electrically?) even though not actually touching.

You can change the touch bar through various preferences, and can even make it revert to the old and simple F1 F2 F3 etc. keys instead of it being so "smart." This may prevent the problem from happening.

For me, I had to fix this on a work 13 inch Macbook Pro from 2017, but on my personal 2019 Macbook Pro 16-inch (like yours), I don't have the problem -- I think the layout and distance between keys and touch bar factors in here.