Biggest downsides to OLED are PWM if you are sensitive to that and the black “smearing” at low brightness. (It’s actually just the pixels being slow)
My LG V30+ was really bad with this and black crush. The LG G8 ThinQ is noticeably better but black smear is still visible on low light.
I don't mind it much but on the XS it was like I had my V30+ again. Not sure about the newer model but I imagine it's still there, if only at lower lighting.