Then it is set to Intel. 
What I said above applies if you are using a dedicated Nvidia or AMD card in addition to integrated Intel graphics.
I did not realize it was only available as flatpak, but am not surprised...
Have you checked the status of avahi?
systemctl status avahi-daemon
If not running, you can use systemctl to start or enable it
sudo systemctl start avahi-daemon
sudo systemctl enable avahi-daemon
Along with Gstreamer, you may need:
sudo apt install intel-media-va-driver
For the Mesa; Vulkan warnings, you might also try
You are logging in on Zorin on Xorg, right? Not Wayland?