74

It’s 0.2 mm and it’s not as simple ans shifting a focus.

Assuming that they simply made the base 0.2 mm thicker without altering the curved side, this still changes beam pattern because light that hits the the air-to-glass boundary refracts and continues inside the lens. Now it’s shifted so literally any part of the beam other than dead center hits the curve lower than it would otherwise - and that part of the curve is being hit at other angle than it would be otherwise.
This seriously changes beam pattern.

I seriously doubt they would change thickness without altering shape. It would be too amateurish, if their supplier is able to produce asperic lenses they surely understands this.
OTR probably simply switched the lens model or maker.
Or maybe tooling to make a different shape would cost too much and OTR thought that some packaging or strength improvements were worth the artifacts.