It seems YouTube is rolling out a new “Stable Volume” feature on its app. The platform hasn’t said what the feature does, and it doesn’t look like everyone has it just yet. The feature was spotted by a few folks, including a Redditor and YouTuber M. Brandon Lee. It reportedly appears under the Ambient mode option on the video settings page.
While it’s unclear what the “Stable Volume” setting does and how it works, the name suggests it controls and evens out volume across different videos. This could help YouTube users avoid a sudden and sharp volume jump or a random decline in volume levels while watching videos from different creators and channels. It’s unclear if there’s any AI involved in how the feature recognizes and optimizes volume levels across videos.

Source: YouTube quietly rolls out new 'Stable Volume' feature