I believe recent version of tbe default iOS Notes app can backup to Google Drive.
Have you ever setup the iOS Notes app to backup to Google Drive?
Those notes should be in Google Drive somewhere.
This is why I stopped using Apple’s free, default iOS Notes app, many years, ago!
Apple only develops this Notes app as an iPad “showcase” app that is only 75%-80% “there” , all the time, to show other third party notes apps developers what can be done with a notes-style app.
Apple never, EVER tries to issue regular updates for their free Notes app during a year of iOS updates.
Apple ONLY updates its own iOS Notes apps only once a year with a major iOS/iPadOS upgrade cycle!
Everyone has major issues with Apple's free iOS Notes app every once in awhile and it is, usually, catastrophic!
Personally, I stopped using the free iOS Notes app for any real important notes many years, ago, and now rely on much better third party paid notes app, that are more feature rich and a whole lot more stable and get many regular app updates from the third party developer and have never looked back!
Many great third party apps that make saving and backing up/archiving my plethora of notes, documents, PDFs and sketches trouble free for many years, now!
I never, EVER trust important notes, documents or sketches to Apple's free default Notes app, any longer.
Through the past years the Apple iOS Notes app has proven itself to be totally untrustworthy in saving my notes content for the long term!