But bad on agile for letting charlatans co-opt the term.
The Agile Manifesto was just a bunch of people who were already doing XP, Scrum or some other lightweight process getting together and writing down the similarities between what they were doing. It's a blanket term invented to describe a variety of different processes, not an actual process.
[1] https://en.wikipedia.org/wiki/Kent_Beck
Just as product requirements can change, so can the way we work. Just like there is not one singular product that solves everybody’s needs, there isn’t necessarily one process that does that either.
I kid, but I think the early proponents of Scrum and similar were trying to achieve a loose framework to do exactly what you’re talking about. The modern incarnations of these can be horrific, but the original intent was always to empower teams to make their own process. Ahh well.
Like so many good ideas (democracy, constitutions), you only really know how well they function once people are actively trying to subvert them. Scrum et.al. have failed in the face of corporatocracy. I honestly don’t know if decentralised structures (i.e. teams empowered to run themselves), can ever survive in large corporates. Which is a pity. Cities grow, but companies die. You have to jump off the dying colossus to find the new company that hasn’t yet succumbed.
You need to communicate with stakeholders then, to change requirements, explain mistakes, set new goals, and reprioritize tasks. Agile (SCRUM/Kanban/etc.) are designed with frequently changing requirements in mind. In SCRUM, this is done at sprint review/sprint planning stage. In Kanban, it's continuous process.