I like it, but I'm unsure if "save" is the correct wording. Maybe "OK" is better?

According to the Material Design Guidelines, I would understand this dialog as confirmation dialog, which should have buttons Cancel and OK.
https://material.io/components/dialogs#confirmation-dialog

I am not yet sure how i want to implement it - either save implicitly, just like the notes itself, or explicitly using a button (as it is at the moment). By the way the favorite state is saved directly, regardless of the buttom you choose - it felt unnatural to only save it after pressing a button...

From various people i learned that the primary button should be a verb rather than just "ok", so the user is more aware of the actual action 🤷‍♂️ but that's just wording, still have some bigger issues / troubles to be solved 😄