Mouse Movement is Jagged

[Coldplayer]

https://imgur.com/a/T7iZhAG

Hi guys, was just doing some testing. I fired up MS paint and noticed when I try go side by side as straight as I can the lines are massively jagged. If you zoom into the pic you can see it skips up and down every once in a while.

I'm using a Zowie fk2-dw but I've also tried with a vxe r1 pro with the same result. Using them both at 1khz. Using a steelseries fk2-dw and there's not too much dust on it. Anyone have any ideas?