Gamepad not recognized

Hi, the non-flatpak version is able to detect the gamepad, but the flatpak version is not.
Tested both with USB and bluetooth.

Basic page for testing is https://gamepad-tester.com

I guess it's a permissions issue, but not familiar enough with flatpak to know how to test workarounds.

My use case is cloud gaming, specially playing GeforceNOW at play.geforcenow.com, which I'm able to do with the non-flatpak version.

Please let me know if there's any info I can provide, though should be reproducible as long as there's access to a gamepad.

Thanks!