Nested sharing could only lower the access rights

Mostly I wonder is it a bug or feature? Is there any special reason Nextcloud work like that? And are there any changes in next releases?

Steps to reproduce

1. Create folder1 and test.txt in it;
2. Give some user read-only permissions to folder;
3. Give the same user write prmissions to test.txt;

Expected behaviour

User should be able to write into file. The closest sharing option should be selected.

Actual behaviour

User has read-only access to file.

Cause

In Cache.php of files_sharing application there is an entry:

if (isset($entry['permissions'])) {
    $entry['permissions'] &= $sharePermissions;
} else {
    $entry['permissions'] = $sharePermissions;
}

If you change AND (&=) to OR (|=), you'll not be able to forbid user something inside the shared folder.
Is there any reason why we can't use $entry['permissions'] to the file?

Nextcloud version: 16

Start with Cache.php in the files_sharing application and trace how permissions from nested shares are combined. Reproduce the folder and file sharing steps, then establish whether the closest share should grant write access without allowing nested restrictions to be bypassed.