OPNSense routes packets out of wrong interface

[Sakreton]

I know the title sounds ridiculous "wdym routing doesnt work" but pls hear me out xD

Background Information
I've set up an virtual OPNSense instance on proxmox 3 Months ago and since 2 weeks been trying to figure out why routing between different vlans behaves very weird.

Screenshot of my Logical Topology: https://1drv.ms/i/s!AioN4YSKYgRFj4s_HZic9KnuoIiaTQ?e=nX9Rah
VLANs are split up in proxmox and handed via seperate NICs to OPNSense, but i dont think anything like this is the problem.

I have set up the following firewall rules, which i dont think cause the problem but still wanted to list them anyways.
My LAN (Vlan1) has an any any allow rule. (Ik not ideal but can't think of a better solution)
And i allow DNS traffic from my IOT net (vlan4) to my pihole in vlan 1. (This is how i initally found the problem)
For testing purposes i have also set up multiple rules to allow icmp traffic from every net to every other net.

Now onto the problem:
When i try to ping from my IoT net to any address withing vlan 1, opnsense routes those packets to my fritzbox.
Pinging the interface of my opnsense for vlan works. Packets pass firewall rules regardless.
I confirmed this by a packet capture of those interfaces and by setting up a static route on my fritzbox back to my opnsense. Those packets coming back are obviously and rightfully so dropped.
I confirmed both by looking in the CLI and in the webgui that the routes to those subnets exist and should forward as expected to their respective interface.

The Initial problem was my IoT devices not beeing able to reach my pihole in vlan 1, i later found out that this problem affects all traffic not just DNS.

Most of the other stuff is working fine, access from vlan 1 to vlan4 works as expected, a few Forwards i created for service available to the internet work as expected.

So i am very confused to say the least.

Similar problems i found online only occured when using multiple WAN interfaces, which is not the case for me.

At this point i have completely reinstalled OPNSense because to be quiet honest this just sounded like some weird bs that broke during an install, i could not believe whats happening, it just didn't make any sense.
The Problem still persists.

To be quiet honest i am completely out of ideas on this so i would appreciate any ideas you might have.

Thank you so much for reading this!
I hope i explained it well enough, if not and you still want to help feel free to tell me whats missing.

[Sakreton]

Okay, after talking to some people i accidentally found out, i falsely selected an upstream gateway on my WAN interface instead of having it set to auto detect