Bad Print in -X+Y quadrant

Hi, Since getting my first printer, the Ender V3 Plus, I have continually got bad prints with a large circular overhang in the -X+Y quadrant. It wasn’t too bad to start with but has got progressively worse. The print starts well with the cylindrical part on the bed and then gets progressively worse as the overhang progresses with increasing Z. The +X-Y quadrant is pretty good. I have tightened the XZ belts but that made no difference. I have a good solid base for the printer. It gets that bad that the nozzle starts to grind against the build in that area. Anyone have any ideas what the problem could be?