After a switch port exits a VLAN, the MAC address corresponding to the VLAN is deleted from the port. During the port deletion process, the system does not process new MAC addresses that are synchronized from other boards. If the new MAC addresses are synchronized to the system four seconds after the deletion is complete, the system receives the MAC addresses and inserts them to the MAC address entries on the board.

You can run the display mac-address command to view the synchronized MAC addresses.

So during those 4 seconds the service wont work am I right?

Yes, thats right, 4 seconds service will not be available until the end process of removing mac-address.

ps. I think there should really try to hit it in the beginning of these 4 seconds