Back in 2015, Sony created the "Sony's Concept for Android" program. The result was something between a beta program and an alternate ROM that offered a mostly-stock Android experience with fast updates. Unfortunately, Sony has decided to end the program - at least for the Xperia X.
The announcement comes from Sony's InTouch community, which has served as the hub for communication between Concept users and Sony since the program began. According to the Concept Team, the final update will come in early May, possibly being a stable version of the experimental 7.1.2 release.
The post also says that the InTouch community will live on for the XZ Premium, but that phone will not receive the Sony's Concept software. The post did not say if the Concept program will continue to receive security updates.
- Sony InTouch