Age-gated vids have been login-walled for a while now, non-age-gated stuff is still viewable while logged out and through alt front-ends, for now.

I won't put it past Google to fully login-wall YT at some point in the future though, or even worse, put DRM on it so that it's only watchable through Chrome on Android, or Chrome or Edge on Windows, and non-Android and non-Windows OSes, and non-Chrome/Edge browsers are blocked, as well as alt front-ends and downloaders, and even mirroring to competing platforms.