we recently set up a firebase hosting-based web-app, which was supposed to transmit its retrieved data to a Google Sheet.

On Wednesday we actively used that web-app for the first time and quickly noticed that the Google Apps Script wasn’t set up properly in its permissions, which is why the data couldn’t be entered into the sheet.

I’ve looked through several threads and haven’t found anything mentioning this – is there any way to find this data in some form of temporary save-file etc. to recover it or is it lost forever?

I set up Realtime Database to store data, though only after the fact and got the lovely response “Null”.
Looked through documentation on Firebase and several Google Support threads as well as a few Stack Overflow threads on tangentially-related topics.

Please keep in mind that I took over this project from someone else and I’m not very well-versed in IT as a whole.