It had major downsides for me. I don’t appreciate any graphics settings being changed. It changed all my settings to low from nearly Ultra. And it kept happening and I couldn’t figure out why. Until somebody else posted the solution, and turning that option off fixed it.
IOW, I had exactly the same experience as the OP.
You probably have a decent system if you didn’t see much of a change.
i7-4790K/16GB/2070 Super/LG 55UN7300 4K TV. It looks at the lowest common denominator and uses that. I run at nearly Ultra (IOW, Ultra across the board except a couple of settings) perfectly happily.
My point was, you implied he shouldn’t check that setting. He needs to check it, it causes exactly the situation he posted about. If it’s already off, then move on from there.