Re: BUG #18526: 'UPDATE' inconsistency using index scan with 'NOT EXIST' after upgrading to PostgreSQL 16

> On Jun 28, 2024, at 10:24, PG Bug reporting form <noreply@postgresql.org> wrote:
> 
> Expected Result: All records that meet the criteria should be updated
> regardless of using index scan or seq scan.
> Actual Result: When PostgreSQL 16 uses index scan, it fails to find and
> update all records. By changing random_page_cost to a value that forces the
> use of seq scan, all records are updated correctly.

Have you tried rebuilding the index to rule out index corruption?