YouTube shows only your latest 5,000 liked videos, and the rest quietly stop appearing in the playlist

Took me a while to work out what was going on here, so putting it somewhere findable.

Liked videos is not capped the way an ordinary playlist is. An ordinary playlist stops dead at 5,000 and refuses the next add. Liked videos goes on accepting likes forever, but the playlist only ever shows your latest 5,000. Past that the oldest ones stop appearing while the thumb on the video itself stays lit, and nothing tells you it happened.

They are not deleted, which I think is the thing to get straight before anyone panics. Google still has them, and unliking a few recent videos makes the same number of old ones come back at the bottom, so it behaves like a window sliding over the real list rather than a bin. You can also get at them outside the playlist, either in the Likes and Dislikes section of your Google account activity or by exporting through Takeout.

What you cannot really do is browse them. A Takeout export is a file, not something you skim on a Sunday looking for that one video, and the activity page has none of what makes a playlist useful. So the data survives and the access does not, which is a strange way to treat ten years of someone saying they liked something.

If you have been liking videos for a lot of years, it is probably worth scrolling to the bottom of the playlist and checking whether your earliest ones are still there. The count at the top not matching what you remember is about the only hint you get.