Why does Xiaomi Mi Router 4C Have 4 antenna?

Why xiaomi mi 4c has 4 antenna and not two beside MediaTek MT7628DAN it's 2x2 spatial stream

For the four ports on the circuit board:
https://openwrt.org/_detail/media/xiaomi/xiaomi-4c-pcb-closeup.jpg

Does it need them, maybe not but it then matches the design of the r4a and r4a gigabit.