Youtube transcoded many old videos to AVC codec instead of retaining VP9

[Zoey.]

Why does Youtube do that when AVC has much worse quality than VP9? I noticed this when my YT video with 50k views got the AVC codec (it was VP9 last year) along with even some videos with over 1 million views on other channels

[Heitor Villa-Lobos]

When did that happen?

[Ysosrscat]

You mean av1?

Youtube retains the original, I've never seen a case where they get rid of h264 for vp9, they always exist together.

H264 is original, then if your channel passes a certain bar then vp9, then if you are further worthy you get av1.

av1 is the most advanced open source codec, nothing wrong with it at all, other than the encode time.