On top of my head, I so far pretty much had:
Armstrong in Sestriere 1999 (first Tour I watched)
Landis Morzine 2006
Contador Verbier 2009
Froome Ventoux 2013
Will have to add today.
Why only TdF moments? Well, thats the race where its just most memorable for me personally.
The TdF is the biggest prize on the calendar, so that's where the biggest pros at the dark arts stuff come out of the woodwork & do what they've got do to win at all costs.
The problem with all of those previous examples you mention is the rivals on those specific days could be handwaved away as not very good for whatever reason (Oscar Pereiro with Landis 2006, Alex Zülle with Lance 1999, Lance & Schleck with Condator 2009 & Contador with Froome on Ventoux 2013).
But one of the most talked about "memorable" performances ever was of course Pog at LPDBF in 2020. A performance Pog just repeated in the Tour today on stage 16... but he still got smashed by Vingegaard. So today was like LPDBF + 1. Like an upgrade on the already unfathomable. So... I'm really at a loss when it comes to naming anything remotely similar to what we just witnessed. It's the most "memorable" one yet, IMO.
And I don't know why Jumbo did it, i.e. 30 seconds + another demolition on Loze tomorrow would have sufficed.