Can't recover not syncronised notes on android

On android client, I have a user who collected and documented notes for over a year in Nextcloud Notes app. That app was over a year ago connected to a working instance of Nextcloud server, but that server has been offline since. The user wants to recover the notes to either plain text file, or a collection of plain text files.

Although Nextcloud Talk is installed (v.3.6.0) and correctly running on an android client, I can find no trace of where this data is actually stored on the android can be found.

Could anybody share any hint how to resolve this issue.
Many thanks!

I assume you are the same user that asked this question in the issue tracker?