GitLab

Both kind of backups (Plaintext and Encrypted) have always been impossible to see and copy from MTP mountpoints, and can only be listed through adb, and pulled with adb. This is much less handy than being able to copy it from your usual file manager, and I see no reason that would explain it to not be visible (enabling the display of hidden files doesn't show them either).

Properties seems to be the same as other directories created by the system and visible through MTP:

drwxrwx--x root     sdcard_rw          2019-11-27 21:17 Pictures
drwxrwx--x root     sdcard_rw          2020-01-08 18:38 Podcasts
drwxrwx--x root     sdcard_rw          2016-06-28 05:15 Ringtones
drwxrwx--x root     sdcard_rw          2020-08-16 10:56 SilenceExport
-rw-rw---- root     sdcard_rw  2166974 2020-08-16 10:56 SilencePlaintextBackup.xml
drwxrwx--x root     sdcard_rw          2019-03-15 05:02 System

EDIT: This could be a more general problem with some datas written by applications as I did backups from Two factors applications too that seems to suffer from the same issue.