This happened to me too. I still use a MacBook Pro from 2015 mostly for watching videos. As you described, any time a subtitle appeared on the screen, the screen fluctuates in brightness / gamma levels.
I guess one other thing you could say is, I don't know if it's just me in my head, but I always feel that the cursor movement in MacOS is silky smooth.
I guess one other thing you could say is, I don't know if it's just me in my head, but I always feel that the cursor movement in MacOS is silky smooth.