HR spikes but doesn’t stay elevated

My resting HR is usually around mid 70’s unless I’m having a bad day. When I stand it will spike about a minute or so after and that’s when I get overwhelmingly dizzy and lightheaded and need to lean on something for a couple minutes. I wear an Apple Watch (and probably need a new one) and I’ve monitored my HR in those moments and it appears that even though my HR will spike to 120’s it doesn’t stay elevated.

This was similar to my holter results where the nurse dismissed the fact that I had some high readings because they went back down pretty quickly. Is this an indication it’s not POTS? Or is this an indication my propranalol is mostly doing its job?