Update Traffic from Firewall itself through gateway group

[downset]

Hello,
i have noticed during the Update to 25.7 that the download Traffic is not using the gateway group and not the default gateway.
I have a dual WAN setup with fiber as main and Starlink as fallback. Both enabled ipv6, with everything routing correctly only through the gateway Group.
But if I check for updates or download updates, the Starlink backup Tier 2 gateway with low priority is used via ipv6.
Can anyone give me a hint what kind of firewall rule I need to prevent this?

greets
downset