well I found out the issue, somehow the game settings self-altereded and disabled vertical sync - lowering fps limit to 100 + forcing vsync corrected it, I did keep the reshader, though, because there were numerous reports of this error related to it, apparently deleting the default shaders folder fixed for many. Meaning that reshader might help on future "issues", who knows.
The plus side is that using it's "performance" setting always helps with most games, so it's a decent tool that I've used many times before, specially for broken engines like Skyrim's Creation engine.... The good thing's that with reshader the game's really running smoother than before, so there's that!