A FORCE INDEX added in 2019 to work around a bad plan choice, still in the query four years and three major versions later.
-- what it was
SELECT * FROM orders FORCE INDEX (idx_status_created)
WHERE status = 'pending' AND created_at > ?;
-- removing it, on 8.0.33:
-- with hint 12ms idx_status_created
-- without 11ms idx_status_created
-- the optimiser now picks it on its own.
An index hint is a decision frozen at the moment it was added, and it survives schema changes and version upgrades that would have changed the answer. Ours had become harmless; the danger case is the hint that forces a now-inferior index and gets blamed on the database. Auditing them yearly is five minutes and found four, of which three were removable.