Building a Go module with BuildGo120Module

I wrote a derivation locally for the soft-serve pacakge, basically taking the package from nixpkgs at 22.11 (in this tag, the soft-serve package was at version 0.4.7) and adjusting the version to 0.5.2.
In my configuration.nix I set system.stateVersion to 22.11
I was able to build it with neither BuildGoModule nor with BuildGo119Module.

I cloned the project locally and tried to build it manually. I was not able to build it with my local go installation from nixpkgs-stable, go version 1.19.3
I ran nix shell nixpkgs#go, which installed go with version 1.20.3, and was able to build the package manually; with go version 1.20.3.

I tried to use BuildGo120Module from unstable while keeping my stateVersion at 22.11.
Does anybody have an idea how this might be possible ?