in the datasheet of LED2001, Figure 20, 21, why the thermal pad and PIN8 not connected on the top layer?

[Dsun.21]

Dear Expert,

from the bottom side, seems to me that Pin4, thermal pad, and Pin 8 all connected to Gnd. but from the top layer, there is a gap between the thermal pad and pin 8. if my observation is true, why not just connect the thermal pad copper and the pin8 copper to improve the thermal performance?

thank you,

David