Where is all the 2.83-2.91 content?

This is supposition on my part but I’m guessing that the changes and versions were coming so fast that these guys couldn’t keep up and still maintain their day jobs.

Having said that, most of the information in the older videos is still valid. Some of the keystrokes have changed but the basics are still good. You can try watching these videos and then go searching on youtube or the blender documentation for how you do that in the version you are using.