On the item Q442838 the following distinct values constraint is displayed: "This property's value should not be present on any other item, but is also present on Marcos Alonso and P442838 (Deleted Property)."
This distinct values constraints refers here to the same item Q442838 althoug displayes as P442838 and refers to a deleted property.
on item Q442838 this behaviour occurs for the all properties used in this item!
I found the same issue for the following other items: Q15478102, Q2568828, Q2544650, Q442838, Q28151216, Q16303051, Q42100656, Q19594154, Q3290522 and 12 more items. and these are just those for association football players.
I conclude that this happens by now to a very big number of items, especially if they were once merged like i found it on item Q60040590 which was merged from item Q62714842.