It should be related.

In the past, lenses had this mark, and now some spectacle lenses are also available. This thing has its pros and cons. The advantage is that it can prevent counterfeiting, but it can also be counterfeited.

The disadvantage is that leaving it on the lens really hinders the light transmission of the lens. We usually move it to the side that can be rubbed away during processing. But sometimes it is impossible to let go.