Weird Vsync frame cap problems

i recently switched over to a new monitor, however my pc is a laptop so the latency between the laptop and monitor can be weird, with this new monitor the game runs at a steady 60 fps however the gameplay is very jittery and not smooth, so i tried vsync, vsync seemingly made the gameplay more smooth and initially capped the framerate at 60 fps however after a few minutes of gameplay the framerate cap seemingly dropped to 30fps. my specs are intel core 7th gen with a GTX1050 Ti and 8gb ram. i was also running the game at all low settings so i dont know why the game is suddenly reducing my fps during gameplay.

any help would be much appreciated Thank You!