Subtractive Brush Question?

Hey everyone I’m curious why the subtractive brush on the left only clips the floor and keeps the yellow beam solid (which is what I want) and on the right, the yellow beam gets sliced?
I’m definitely missing something and would really appreciate learning why this is happening.



Found the answer was layering - thought it had to do with that, didn’t know it exactly but now I do. Just posting a lil gif for anyone else in the future that may have a problem.