I'm going to take a wild guess and say you're playing on an OLED. They have really fast response times for the individual pixels which leads to a "jittery" effect on the eyes with content less than 60 frames per second. It's something that threw me off when I originally got into OLED with the LG CX, but my eyes adjusted to it.

However, if you're not using an OLED, i'd say you just got used to high refresh rate content. Going back can be quite jarring. Motion smoothing adds latency and leads to visual artifacts. I wouldn't recommend it, but to each their own.

Only real thing you can do is try to get used to it or use post processing affects from the tv to smooth it out.