What program did you design and produce the G-code with? If you designed in LightBurn there shouldn’t be any Z moves. On the other hand if you designed in Vectric or similar software aimed at routers you need a special post processor that eliminates Z moves. JTech has a post processor for Vectric to make laser G-code.
If you don’t use Vectric, or don’t want to mess with post processors, I would recommend exporting your design as an SVG and then importing that SVG into LightBurn and let LightBurn make the G-code and control the laser. It’s probably better to use LightBurn in any case because you can set a Z drop per pass when cutting so that the laser focuses deeper into the cut on each pass.
There shouldn’t be such a ‘drop’ in the lens and I’ve seen this before. Check out this thread.