I know you didn't want to focus on form, but I'm going to share my experience with the same recent issue. I just got back into archery in earnest this past March after a >5 year hiatus. I was consistently hitting left of my poa with both a recurve and a longbow. Both bows were new to me, and I was also working with carbons for the first time as they are apparently more prevalent now. So I was very frustrated trying to find an arrow that would work with both bows and diagnose why I kept hitting left. One night I read about using a "deep hook" on this forum, and realized I was doing it wrong. I'd always shot off the pads of my fingers. With a deeper hook, my groups snapped to center. And it's completely repeatable, if I shoot off my finger tips again my arrows move left. Deeper hook, back to center. I did find that a GT Traditional 400 works for both bows, the recurve likes a 125gr point and the longbow needs 175gr.
30.75" draw
Recurve 45lbs @ 30"
Longbow 38lbs @ 28"
Good luck, I hope you get it solved!