Media pause/ playback not working anymore with KDE Connect in Firefox. How can I fix this?

I've noticed this issue for a few weeks now, but hoped that it is just a bug and will be fixed soon.
Sadly, this doesn't seem to be the case, so I decided to post this issue here to find solutions.

When I play a YouTube video for example, it shows me everything that's playing right now, and the current status (paused/ playing).
Sadly, I can't manually stop or resume it with my phone, which sucks because I then have to get my lazy ass up the couch and pause it on my laptop a few meters away :D
Or, I have to unlock the phone and use the remote input feature, which is annoying too...

I already checked the Flatpak permissions, the settings in KDE Connect (both on my PC and phone) and looked up on the internet for that problem, where I found both too much and nothing at the same time.

I think it's because of Firefox, because if I play a song on Spotify for example, it works fine.

Do you experience this issue too? How could I fix it?
It appeared out of nowhere, probably due to a update, I didn't do anything that might have broken it.

::: spoiler Software used and advanced information

Distro: Aurora (Fedora Atomic, uBlue), stable
Firefox: Flatpak
KDE Connect on Android: downloaded from F-Droid, always newest version
Issue since: about 3 weeks
I already tried to update everything manually and rebooted many times, both my phone and PC. :::