This issue only needs to be tested in 1 device. You need to be able to edit the Moodle's database. Edit the Moodle database to include  CoreMainMenuDelegate_QrReader in disabledfeatures. The easiest way is to add another disabled feature via UI, then go to the database, table config_plugins,  search the disabledfeatures setting (plugin is tool_mobile) and change the value to  CoreMainMenuDelegate_QrReader . Purge caches. In the app, login in the site and go to More menu. Check that you don't see the "Scan QR" option. Remove the disabled feature in Moodle. Restart the app and go to More menu. Check that you see the "Scan QR" option.