Covered in detail in this comment on WT-13166. We have a WT_CURSOR_HS history store cursor that is being incorrectly cast to a WT_CURSOR_BTREE, so accesses to WT_CURSOR_BTREE fields are actually reading the contents of different WT_CURSOR_HS fields.

The code needs to be updated to correctly fetch the btree from a history store cursor, or possibly removed.