Htmx is a rebrand of intercoolerjs, which is just as old as react etc.
Tanstack is just an alternative layer ontop of react or solidjs. You're fundamentally still using them. It's just a diffent implementation for eg routing or state management.
So no, none of those could be considered fotm like the grand parent insinuated.
And that's ignoring how both tanstack and htmx are also over 5 yrs old, respectively. Even under these names.
That's why I use NextJS... it seems to be the clear winner for React (at the moment at least).
Tanstack Start seems to be gaining steam.
At least many are in the react family though, so switching is less of a pain than Ember to React, for example. And especially so with agents now.