Noticed the same on all my chromecast audio devices. Today got a mail from google that they are working on fix. Reddit/ google search gives insight as issue being CA certificate of these devices expired on March 8-2025. So easiest fix given is ( not tried myself) is to re setup the device from android phone after changing date to anytime before March8-2025.
I m not so affected by the issue, so waiting for google fix to apply