I think you're overestimating Pakistan's capability. It gave Taliban leaders shelter at their worst moment, and that is about the only leverage ISI had.

The moment Taliban started to carve out territory inside Afghanistan, that leverage was gone. There's some gratitude, but also lots of resentment among Taliban leadership about the way they were treated by the Pakistani authority.

Yep, totally right. I think you need to also tell about Afghan government itself "returning Pakistan a favour," and dispatching the Pakistani Taliban.

The amount of support Pakistan provides Taliban is severly overblown. Did they provide them refuge when Taliban was on the back foot? Sure, probably.

Is Pakistan aiding them in this current offense? It really doesn't seem like it.

ISI help is significantly more than refuge. That said, the Taliban didn't need help for this offensive. They've been handed the country on a platter.

I don't know that much about the region, but the us-supported side had 20 years and lots of money to prepare for this day. I would assume if they enjoyed more popular support in the near past they would have built something that would less obviously be the losing side today, and people wouldn't have jumped ship so quickly.

The US built their side so as to maximally depend on them and then pulled support abruptly, while all but grovelling to the Taliban in public. There could have been no other result the way this withdrawal was done.