I subscribe to AvE and he has done a seemingly good post-mortem here.
Part 1: https://www.youtube.com/watch?v=ioC61QW7SHQ
Part 2: https://www.youtube.com/watch?v=KtiTm2dKLgU
Looks like he took a combination of comments to his Part 1 video, Reddit and other sources and communicated the current theory.