[zamadatix]

You don't need high res for HDR on YouTube (144p HDR is a thing there oddly enough) and the 4k version had already processed when I posted that comment (with no change since in HDR availability). Usually media announcements/large channels pre-upload the video so it's ready when they want it to actually publish to avoid that kind of issue though.

[dannyw]

They probably use 144p for automated systems like ML recommendations, moderation and content ID.