My biggest issue right now is just a complete lack of consistency, and I guess that also goes into what you say in that I often don't know what I've done 'wrong' one time compared to the next.
An example from yesterday on a par 3, that actually turned out to be my best result. First shot off the tee with a 6 iron I thought I did my normal setup/swing but must've hit it off the toe as it went 45 degrees to the right, thankfully onto another fairway so easy to see/hit. Next shot basically 10 yards closer but 40 yards or so off to the right I pick a 7 iron, partially for loft as I needed to get it over a tree rather than the difference in distance, I feel like I setup/swing the same but this time it's beautiful, bit left of where I thought I was aiming but the shot is straight, easily clears the tree and ends just on the fringe/edge of the green. Then I two putt for a bogey.
Just no real idea why that first tee shot went completely wrong
Was I setup too far from the ball, did I lift my spine angle during the backswing, was it the main swing, was it something else, I don't really know tbh...