On the following Ubuntu:
Description: Ubuntu 22.04.2 LTS
Release: 22.04
Codename: jammy
Backup files are located in:
/home/$USER/snap/notepad-plus-plus/common/.wine/drive_c/users/$USER/AppData/Roaming/Notepad++/backup/
$USER is used to get the current user name in your system.
In my case,
$ ls /home/$USER/snap/notepad-plus-plus/common/.wine/drive_c/users/$USER/AppData/Roaming/Notepad++/backup/
'new 1@2023-07-24_131201' 'new 1@2023-07-25_225938' 'new 1@2023-07-27_000008' 'new 1@2023-07-30_215759' 'new 1@2023-08-01_145110'
'new 1@2023-07-24_154340' 'new 1@2023-07-26_220545' 'new 1@2023-07-28_122836' 'new 1@2023-08-01_120730' 'new 1@2023-08-01_145923'
On the other hand, you can view and edit your backup path for Notepad++:
Open Notepad++ and click Settings > Preferences > Backup
In order to avoid previous session snapshot case, I modified it as:
Backup on save > Verbose backup > Custom Backup Directory > C:\users\USERNAME\Desktop\BackupNotepad
Instead of "C:\users\USERNAME\Desktop\BackupNotepad", place directory whatever you would like. Verbose backup basically adds a timestamp when saving the file.