https://www.techradar.com/news/youtube-tv-now-supports-firefox

Interested in trying YouTube TV, but don't fancy switching your default browser to Chrome? Good news - you can now stream shows to your desktop using Firefox instead.

Until now, Chrome was YouTube TV's only supported browser, but eagle-eyed subscribers at Your Tech Explained noticed that Google has updated its support page to include Firefox in its list of options. The change isn't yet reflected on the actual YouTube TV site, but we expect it will be updated soon.