Hi, I noticed that 120fps is the standard nowadays and there are even some rules in place that allow switching to lower framerates at specific spots. If my pc can only run at 60fps, would that invalidate my run or simply put me at a disadvantage?

Thanks in advance for any clarification! I am fairly new to this but am excited to learn a few speed games for the sake of marathoning them :)

Your runs will still be valid. You will lose a bit of time over the course of the run, but it won't stop you from getting good times.