Deleting a contribution does not release the slug for further use.

[Deleted user]

softdelete hook triggers but it keeps the slug for the contribution "reserved" - hence a contribution with the same slug cannot be created ever again.

Possible solution: randomize slug on softdelete or add a number to slug on create if exists.

[appinteractive]

The issue is not the releasing part but that the slug should add an increment until it's available. Seems that this is broken (or disabled) somehow.