Video files in quest2 are no longer readable.

I am developing an app that uses Unity to browse and play videos stored inside Quest (/mnt/sdcard/movies).
Due to a recent update (either 51.0~53.0), it suddenly stopped working on all 5 of my Quest2 units. It works fine on devices that have not been updated since version 49.0.

I need to know how to deal with it.