Wayland Protocols 1.27 Brings Content Type Hinting, Idle Notification
The two new staging protocols with Wayland-Protocols 1.27 are for content type hinting and idle notifications.
The content type hint notification is used for enabling clients to provide hints to the Wayland compositor around the type of visual content provided by the app. In turn the content type hint notifications can be used for the compositor to adapt its behavior. This content-type-v1 protocol was originally written last year and initially supported "content types" are photo, video, or game content. If hinted to be game content, the compositor may optimize for reduced latency, if video it may be optimized for reduced stuttering and better scaling, or photo type for minimal extra processing by the compositor. With this content-type protocol still being in staging, it's possible other content types will still be added but ultimately is left up to the compositor if/what to optimize based upon the various content types.
The other new protocol working its way out with Wayland Protocols 1.27 is the ext-idle-notify addition that has been in the works for several years - all the way back to 2015 when started on it by KDE developer Martin Gräßlin. This protocol allows clients to be notified when the user is idle, so there can be optimizations around power management or other behavior changes when the user is idle.
That's basically it for new material in Wayland Protocols 1.27. The brief release announcement can be found on wayland-devel.