Initially, the affected table only had a date field as partition. So I partitioned it with country and date fields. This new partition created the country and date directories however the old directories of the date partition remained and were not deleted.

Apparently these directories were causing the conflict when trying to read them concurrently. I created a new delta on another path with the correct partitions and then replaced it on the original path. This allowed old partition directories to be removed.

The only consequence of performing these actions was that I lost the change history of the table (time travel).