That's really weird... I play Rocket League on 144 frames and X is far more janky.. while Wayland keeps a very smooth 144 99% of the time, and input delay feels non existent but on X it feels like 2-3 frames behind.
Also, did you enable VSync on both the tests? And the same form of VSync? That can have an impact on input lag.
edit: I recall reading about timing experiments. IIRC good participants could get down to 10ms accuracy when trying to time moving their finger to a signal.