Do I need the firewall in relayd configuration?

Hi Experts,
I have been using a classic relayd (Repeater) configuration on my Archer C7 V2 for years and am very satisfied with it. I use a Fritzbox 7590 as an ISP router, which as far as I know has an SPI firewall in use.
Since the Fritzbox already has a firewall, I havent defined it in my Openwrt relayd repeater.
Was that a mistake?
Do I have any disadvantages as a result?

regards Klaus