What is the orange “drama/theater” mask at the top of the Apple Watch screen?

It is called Theater Mode:

Theater Mode is a feature that once enabled, keeps your Apple Watch silent and its screen dark. If you have your Watch set to wake when you raise your wrist, this will be disabled when in Theater Mode.

You are in Theater Mode

Status icons and symbols on Apple Watch

It silences is your watch say when in Theatre does light up or make any sound when you have notifications.