He put a video up about this a couple of weeks ago, and rather than YouTube's algorithm being to blame, it was more him struggling to keep up with his audiences constant demand for more progress with more super sketchy features that he was basicly building constantly.
"the Algoirithm" often gets sited, but it's often a youtuber's interaction with thier audience, the pressure to keep up with demand, rising success and not wanting to miss out.
Do they give you the data to know? I assumed he meant that impressions had gone way down so people are not even seeing it (and why everyone begs you to subscribe and hit the bell). Of course impressions could be restricted because people stop watching after 20 seconds.
Another once great channel (the loam ranger) did a deep dive into the phenomenon of why mountain bike youtubers were struggling with the old format.
Its nuanced, part safety, partly that its a tonne of work to produce good content when you can simply switch to fluff pieces like Berm Peak
https://www.youtube.com/watch?v=nNiCtWoGonw
"The Algorithm" doesn't reward hard work, imho part of the math is our short attention spans... there's only so many time you can watch someone else vlog from a sprinter in Squamish.