According to the FAQ, the "Low Quality Posts" review queue is populated with posts that are either automatically suspected by the system to be low quality, or by posts that have been flagged as low quality.
I recently got a 7-year-old posts in the "Low Quality Posts" review queue. I would assume that, if an automated algorithm determines the post to be in need of review for low quality, it would have made that decision already 7 years ago. So I believe this was the result of a flag.
Question: am I right to believe that all very old posts in the "Low Quality Posts" queue are there because of a flag, or can it happen that the automatic algorithm suddenly changes criterion and marks an old post as low quality?