Yes, this. The high-end M1 iMac shipped with a cooling system more powerful than the M1 can possibly benefit from, and everyone was sure a new MacBook Pro was coming by WWDC. The chip shortage seems like the most likely explanation for both.
The problem was Jon Prosser who was telling all the YouTubers it was going to happen. Even though he's been seemingly wrong as many times as he's right.
It’s a bit more nuanced than that. From what I understand it’s ripples from higher up in the supply chain that are causing delays (substrate, power components, etc.). TSMC on its own is doing fine.