It's currently in Last Call, but if there's consensus to modify HTTP/3 that can be done at any point, although obviously doing it after it's actually published would be in the form of errata or a -bis RFC that modifies the standard. It's not extraordinary for something which has consensus to get done really late, even in AUTH48 (a notional "48 hours" for the authors of the document to fix any last little things that often lasts rather longer than two Earth days) if that's what people decide is necessary.

But "Blink doesn't want to do it" isn't consensus on its own, this page suggests other clients implement this and offers no opinion about whether they intend to likewise deprecate the feature.