bad nocks will do that
if nothing else has changed , thats one guess

string stretch will allso effect arrow flight

It seems like I'm always experimenting with a different set up. This year I tried using vanes and a whisker biscuit and could shoot well at 10 and 30 yards but at 20 yards my arrows were about 4 inches to the right. (I;m LH) I tried with my knocking feather straight up and I tried it out to 90 degrees and I still wasn't getting good groups. I stripped the vanes and went back to 3 inch feathers and one of my arrow star rests. I think I'm going to stick with what works, at least for now.

Bobby