Form and input elements are a very standard thing, and while you can certainly do crazy stuff with it, even a simple check if you typed into an input/textarea, or changed a select without submitting the form element, should be sufficient.

I guess the problem might be detecting the submission (because oftentimes there’s custom logic for that) but maybe better just display the warning than lose data. Worst case you’ll just ignore it, best case the devs fix it so that it doesn’t show up when it shouldn’t.