Users of Google’s second-generation Chromecast and Chromecast Audio devices continue to experience casting issues, with many reporting “untrusted device” errors. This problem, which prevents authentication between the devices and Google services, is caused by an expired security certificate (SSL). Google has acknowledged the outage and is working on a fix, advising users not to perform factory resets as the issue is not related to the devices themselves. The company has urged affected users to remain patient as the issue is resolved. This disruption has sparked frustration among users, especially those relying on Chromecast for streaming services.

Google responded to the outage issue by stating
We're aware of an emerging issue impacting Chromecast 2nd gen and Chromecast Audio devices, and we are working on a fix.
Do not factory reset your device - we will keep you all updated when the fix rolls out. If you have already factory reset your device, we will provide instructions to set your device back up as soon as possible.

Thank you for your patience.