The flag is attached to a stream by a Roon Radio Curator to signify that a stream is geo-restricted. Only a curator can do that.
There is currently a bug in Roon affecting a small number of people whereby such restrictions are being incorrectly applied. Until this is fixed, the flag is being temporarily removed. In the case of the BBC, this does not enable non-UK people to receive the stream as the BBC will still block it.
Chris is a curator and removed the flag (although there is some confusion because I had removed the flag some 3 weeks ago).
I see you are in the UK; are you having trouble with the BBC streams?
Yes, I removed the flag where I found it on BBC Radio stations I also added the NB advice on high quality streams being restricted. I can replace the flag easily enough when the bug is fixed.
A little house keeping…