The procedural damaged glass was created using an alpha mask in the opacity channel.
Opacity and SSS controls in the material instance.
I used Substance Designer and Photoshop to create the design of the stained glass window decal. The final material with adjustable glass damage was built in Unreal Engine. This was developed for my ongoing UE5 Castlevania remaster project: https://www.artstation.com/petermai/blog