Incognito mode has been a standard feature for browsers in the past few years. YouTube app is reportedly testing an Incognito Mode that won’t keep track of your watched videos.
YouTube automatically saves your viewing history and ties it to your account. By doing this it can recommend videos or suggest ads, but sometimes you don’t want that. With Incognito Mode on, all your activity from the current session is not saved and subscriptions are hidden too.
It’s as if you were signed out without being so, and there’s a neat incognito icon replacing your avatar. If you turn off Incognito or become inactive on YouTube, you’ll be back to using your own account.
According to the above screenshot, Incognito Mode will show up when you tap your account avatar in the top right of the app. Currently, you will see Switch account and Sign out as two different items, but they may soon be bundled into one, with the empty slot being given to Turn on Incognito.
There has been no official confirmation or announcement regarding Incognito for YouTube yet, but it looks like it might hit Android soon.