Mostly, I'm not big enough to trigger anything there.
Also, since ISPs usually only get a single humongous IPv6 block, it's actually pretty hard to know what is okay to block. Somebody might be on a /48, /56 or /64 network but they might also just have a single IPv6 address. Since you're blocking quintillions of IP addresses with each /64 net, the risk of hitting innocent IPs is high.
Also also, I'm not sure if Google is actually prepared for such a case. Since all the requests coming from Invidious just seem like legit unauthenticated requests, it's hard to flag them on IPv6 when the IPs are fully randomized.
Still, Google is moving towards requiring a login for everything. So I assume that method won't work for much longer.
Besides what was mentioned below, it's not about making competitive products but about Nvidia being an absolute asshole since the 2000s and they got even worse ever since the crypto and AI craze started. AMD and Nvidia are both corporations but they are not even playing the same game when it comes to being anti-competitive.
There's a reason why Wikipedia has a controversies section on Nvidia: https://en.m.wikipedia.org/wiki/Nvidia#Controversies
That list is far from exhaustive. There's so much more about Nvidia that you should remember vividly if you were a PC gamer in the 2000s and 2010s with an AMD GPU, like:
Nvidia has been gimping gaming performance and visuals since forever for both AMD GPUs and even their own customers and we haven't even gotten to DLSS and raytracing yet.
I refuse to buy anything Nvidia until they stop abusing their market position at every chance they get.