Chromecasting from MacOS has been broken for 6 months now - no fix in 15.4
This has been an ongoing MacOS bug that started last October, there are multiple discussions addressing the issue, see below:
"To cast, give Chrome access in system se… - Apple Community
Unable to Chrome cast to my Google TV sin… - Apple Community
Chromecast not working after macOS Sequoi… - Apple Community
Local network blocks apps despite given p… - Apple Community
How can I disable "Local Network" permiss… - Apple Community
The Chrome developers have concluded that it is a MacOS issue with privacy and security settings and access to the Local Network. There have been many workarounds posted, including installing a fresh version of Chrome, turning on and off experimental flags, toggling the firewall on and off, etc. Some of them work and some of them don't but none of them are permanent fixes, they only work until a reboot. I've tried it all and nothing is working. I can't believe this issue has been allowed to persist for 6 months now. I had a lot of hope that the release of 15.4 would fix it, but I'm starting to lose hope that it will get fixed at all and it's very frustrating.
MacBook Pro 14″, macOS 15.4