Group style is weird.

[da jeong kim]

Photoshop version : 20.0.7

First photo : Group style is off. seems nothing wrong.

Second photo : Group style is on. Line and shadow seems weird.

Another files occur same problem. Group style isn't work right.

[davescm]

Hi

Try going to Preferences >Performance and check Use Legacy Compositing

Dave

[JJMack]

If by lines you mean strokes effects.  The stroke would be for the composite of all the layers visible in the group composite. Black stroke on group red stroke on layers.