Chain alignment on jockey wheel
Check the derailleur hanger alignment, and that the derailleur is mounted properly without the bolt being cross-threaded.
You can check the derailleur alignment by eye. Pick up the back of the back of the bike and look down the line of the top run of the chain. (This can also be done with the bike upside down).
The derailleur cage should look like it is parallel to the chainrings. Often the bottom end of the cage can get pushed inward.
If the hanger is bent a bike store can re-align it for you with a special tool.