Absolutely. Audacy has a trademark on "KNX" in relation to anything related to "radio broadcast services."If KNX really is bothered by those streams, they will inundate the operators with lawyer letters and claims, making the streamers incur legal costs. The idea is to make the expense of keeping the name so high that they quit using it.
This means "KNX FM 93 - The Mellow Sound" is technically in violation of Audacy's trademark.
If Audacy wanted to pursue legal action, they could. But the key is really just filing a "cease and desist" and threatening legal action, which should be enough for the streamer to change their name.
This may actually end up happening, considering a search for "KNX FM" leads to the "The Mellow Sound" website as the #1 result. SEO is everything.