Problem is linked to the newer generations of the Intel processors. A fix for it is listed here. https://github.com/ValveSoftware/Proton/issues/8751#issuecomment-2945876353

Switching cpu's performance profiles to performance (using cpupower for example) was a first minor fix for me, elevating fps to 40s. gamemoderun can not be used as a launch option, since it seems to attach to the EAC loader and crash it. So a global gamemoded -r can do the trick. Make sure it has the permission to change the performance profile of the cpu cores.

Additionaly adding intel_pstate=disable to my bootloader config (GRUB) solved final part and makes the game run at 60fps playing multiplayer.

This will not disable the e-cores as many suggest, but disable Intel's driver and load a more generic one, in my case acpi-cpufreq.

Can not really recommend out of the box, since adding the intel_pstate=disable to my GRUB boot loader led to a failed race condition for the NVIDIA drivers using nvidia-drm.modeset=1 next to it. So i had to add the modules manually to the mkinitcpio.conf and rebuild it - which led again to problems of partition size for the boot partition, which was resolved by removing the fallback build from the presets in mkinitcpio.d