Change record status: 
Project: 
Introduced in branch: 
11.0.x
Introduced in version: 
11.0.0
Description: 

Views used to duplicate custom classes like my__class added in the views UI into an additional my--class as a backwards compatibility layer.

This backwards compatibility layer has now been moved to the Stable9 theme. If you were relying on these classes, you should either update your CSS to target the correct class, or add Stable9 as a dependency of your theme

Recommendation is to target correct CSS classes.

Impacts: 
Themers