Qol Clean Slice Booleans
Is it a modifier ?
Nope ! It's a modelling tool/operator.
Once you've used the tool and its options, the boolean is committed to the mesh. The modifier stack for the object is collapsed at that point.
Note: Having said that, there is an option if you own QOL-The Full Collection:
"Commit Blender Boolean". This allows you to use a standard blender modifier right up until the point you may want to clean up buckled normals. If Blenders own modifier works with no buckling, then no need ! :)