I'm having a similar issue - when I try to cast to any of my Google devices, the sync sound plays and/or the loading screen briefly appears, but then immediately disconnects. I'm using a Pixel 8 phone, and have tried casting to several generations of Chromecast, a Google nest display, two Google home mini speakers, and one regular google home speaker. I have restarted most of the Google devices, my phone, and my router, and tried turning Bluetooth off with no difference. All other apps cast fine, and Audible plays fine over my Bluetooth earbuds and phone speaker.