Hi,
Loaded the area into JOSM and ran the validator. Moved a few area nodes and reran, no problems on the simple polygon residential area, properly closed, no self intersections or overlap reported on the item.
Then ran a Shift+V to validate all that was fetched and got a boatload of warnings. There’s a path mapped top of a footway on the north side curve.
The cause of the problem could lie in some inter-area overlaps like here
here in close up where a residential area crosses over the outline of your main residential area
