Lag causing the game to be in slow-mo

Hi,
my game is lagging so much that all the players move in slow motion. This is both online and offline. I've tried every single thing i could think of from game settings to drivers to pc settings to my graphics card and so on. Nothing seems to work and i am now ineligible for a refund. I've used overlays that say i'm maxing out my CPU, but not my GPU. Maybe this is the problem.
My specs are:

Windows 10, AMD Ryzen 5 2600X Six-core, 16 GB RAM, GeForce GTX 1660 Super. I have a 144 Hz monitor.

Any and all help would be appreciated.