The built in inverted color lookup table is off by about 1% lightness value. It's most noticeable if you use it to invert an opacity map setup since otherwise the difference is barely perceivable.

I made an image showing this here though not sure if uservoice compresses or not, the lens studio blackest color is #030303 vs a proper inverted lookup table made with photoshop accurately obtains #000000. Tested in lens studio and the photoshop one did fix it.