Per https://wiki.openstreetmap.org/wiki/Key:building:flats

`building:flats` is the count of flats/units in the building so in this case it should be 4 not 4321.

`addr:flats` is for the range of flat/unit numbers at the address so it should be 1-4.

I've fixed this here and merged the lone address node for the building into the building way which already had the same address tagged.