Speaking as someone who never learned well from courses and always preferred documentation and 'just doing it': I wonder how much of this drop is 100% LLM usage by devs vs. devs realizing a lot of video content was just padded out anyway.
When you hear the phrase "but first we have to go back to..." on YouTube, you're entering a filler section to allow more ad content.
I for one mourn the loss of these and other blogs and am not exactly sure the trade was worth it. Not with the cretins in charge.