>I'd say the old index tuple was killed during the first scan:
>https://www.cybertec-postgresql.com/en/killed-index-tuples/<https://www.cybertec-postgresql.com/en/killed-index-tuples/>
... from your blog: "Whenever an index scan fetches a heap tuple only to find that it is dead (that the entire “HOT chain” of tuples is dead, to be more precise), it marks the index tuple as “killed”. Then future index scans can simply ignore it.