It is a rule in Germany, I know about it because we did some distributed cooperation stuff with community radio stations and some hacking events during the pandemic, and making sure that no matter what happens with the network between the speakers, the coordinating host, and server of the radio station, we never send out silence, was quite an important concern. I can't quote you the exact line of the law,though.
Have a link or info on this? Sounds interesting but can't find anything.