Odds are it's a simple trim problem. The cable is adjusted too short and the RD trimmed slightly inboard of the center of the sporckets. In theory it should affect all sprockets equally, but in practice it varies sprocket to sprocket based on subtle differences including the distance from the jockey wheel to the sprocket.

The fix is to turn the barrel adjuster inward toward the RD (clockwise if looking from the top) a bit to slacken the cable slightly. Very little is needed, so start with a quarter turn, and see how it goes. Be sure to check shifting in all gears, then fine tune in either direction depending on the changes.

BTW- this kind of problem doesn't develop by magic, so it it used to be OK and now isn't, odds are the hanger got bent in slightly. That's probably OK, but it means the entire RD is now inboard a bit, and you need to confirm that there's no possibility of shifting the chain into the spokes. Do this by having someone hold the wheel off the ground, and while pedaling, shift the RD by drawing the cable away from the frame like a bow string (disregard levers for this test). You want to shift rapidly into low, and repeat shifts from 2nd to low a few times to ensure that all is OK. If it overshifts, or even if the chain rides the tops of the teeth as if getting ready to overshift, you have to adjust the limit to stop this.

You might want to seek out tutoials on how to adjust a derailleur, so you have the full picture.