Starting in GoneMAD Music Player 3.3, the "Manage External Storage" is now required for Android 11 and newer. Updates on Google Play require the apps to now target Android 11 or higher, which severely locks down storage access to apps. Google forces apps to use an API called the Storage Access Framework or the MediaStore API in order to access media files on your device. Unfortunately, both APIs are not adequate enough for GoneMAD Music Player to function correctly. Core functionality like playback of certain audio formats, lyric support, cue support, and others completely break with no alternatives when limited to these APIs.
Fortunately for GMMP, Google has granted permission to use the "Manage External Storage" permission which gives the app to the device's storage in order to discover and play all the formats / filetypes users have come to expect. Keep in mind, prior to this 3.3 update, GMMP already had access to the filesystem completely. Targeting Android 11 is what removed that access for apps unable to request the previously mentioned permission. Furthermore, the process to get Google's permission to use the "Manage External Storage" permission is quite intensive. GMMP in particular was in review for 3-4 weeks before permission was finally granted.