I have Galaxy A70 since May 2019, pretty satisfied.
Model SM A705MN,
I was able to listen any Internet radio and in the same time was able to open second window to get i.e. news. And this for unlimited time, unless I turn it OFF.
Suddenly, after a few months, I cannot use this feature any more.
What kind of radio internet app you using, I think maybe your radio app doesn’t support this feature any more, try to find another radio app to use it from the google play, it should work