Hi @PhDittmann,
Looks like there is an ABI issue with WebRTC and LibVPX on UE 5.4 on Linux.
Can you try transplanting this collection of files on top of your Unreal Engine Linux source code and then recompiling the engine.
https://drive.google.com/file/d/1Ny8z9I2KzK_ywoBEnQnP0rVBU-vM-I4G/view?usp=drive_link
Let me know how it goes.
Regards, Luke.