@victoria your lovely support team was able to help me out!
They made a copy of my minimal reproducible app and module, and made a change I had not considered - and it worked!
I'm still not sure how it actually works, but passing in a "Temporary state" and using it as the "Default value" on an input in the module - causes it to reset on submit!
I'd still love for a better or clearer way to do it, like a "Method" or "Event" input type on modules, as this feels like a workaround, and not intuitive (for me, at least) 