Timestamp "modified time" is not the same after copying files or folders

Hello,

the timestamp "modified time" is not the same.

1. When files and folders (without sub folder and files) are copied from internal storage to external storage such as an SD card in the SD card slot or to a USB flash drive (OTG). When files and folders are copied from external storage (SD card or USB flash drive) to internal storage (Android device).

For point 1 there is another file manager app (without root) on Android which does not have this problem. This means that the timestamp for "modified time" remains the same after copying as the source file or folder. Should I say the name of the app or is it not allowed to say it?

2. When folders (with sub folders and files) in the same internal storage of the Android device are copied e.g. the folder Download (/storage/emulated/0/Download) is copied again to a new path in the same internal storage e.g. to (/storage/emulated/0/Backup).

3. When accessing external storage on the Android device e.g. the SD card to copy files or folders (with sub folders and files) only within the same external storage.

4. When files and folders (with sub folders and files) are copied from internal storage (Android device 1) to another internal storage (Android device 2).

For point 3 and 4 the Android system must support it? How do I do that? How can the Android developers get this information to fix the problem?

Tested with Material Files (1.1.2)

No source file, test, or entry point is named. Reproduce the four copy scenarios described in the issue with Material Files 1.1.2, comparing modified timestamps before and after each operation. Done means determining whether the timestamp is lost by the app or Android storage APIs and documenting a specific, reproducible fix scope.