I don’t have words for this. 
It is actually a rectangular illuminated surface. A round glass pane was placed on top of this and the area around it was filled with white silicone, which created the design we saw earlier.
I have never seen this before, and it seems extremely illogical to me. After all, this eats up a lot of efficiency because part of the luminous flux is simply lost (at least it can no longer be used for the lighting in the optics).
Does FFL realize that they have been given an LED that could actually be much more efficient if it had been designed properly? I don’t want to accuse the manufacturer of anything, but somehow I get the impression that hardly any effort has been made here.
Fictitious dialog with the contract manufacturer? 
“FFL wants a round illuminated area in the 3535 LED” - “shit, we don’t have round chip for 3535 LED” - “well, let’s just take the rectangular standard flip chip design and cut it out round and mold the rest with white silicone” - “perfect, no one will ever notice this, for sure”