CGO compilation error: invalid flag in go:cgo_ldflag: -Wl,--enable-stdcall-fixup

Question

In the past, this call worked fine to compile a 32 bit version of my app for Windows (using cygwin/mingw). Now I get an error:

    CGO_CFLAGS="-I/Users/Volker/src/includes/third-party/
    -I/Users/Volker/src/includes/C/util/include "
    CGO_LDFLAGS="-L/Users/Volker/src/includes/third-party/ -lmyApp -Wl,--enable-stdcall-fixup"
    GOPATH=c:/Users/Volker/src/includes/go GOARCH=386 CGO_ENABLED=1
    go build -ldflags "-X main.version=2.0.0-7098 -H=windowsgui" -o myApp.exe

(Note: I added linebreaks to for better readability. It is all in one line and a single call.)

Error:

    go.company.com/myApp: invalid flag in go:cgo_ldflag: -Wl,--enable-stdcall-fixup

The thing is, that if I remove the linker flags it complains about, it complains, too:

    C:/msys64/mingw32/bin/../lib/gcc/i686-w64-mingw32/13.1.0/../../../../i686-w64-mingw32/bin/ld.exe: warning: resolving _ElementEventProc_cgo by linking to _Elemen
    tEventProc_cgo@16
    Use --enable-stdcall-fixup to disable these warnings
    Use --disable-stdcall-fixup to disable these fixups
    C:/msys64/mingw32/bin/../lib/gcc/i686-w64-mingw32/13.1.0/../../../../i686-w64-mingw32/bin/ld.exe: warning: resolving _SciterHostCallback_cgo by linking to _Scit
    erHostCallback_cgo@8

So it is wrong if set and wrong if not set?

The only thing that has changed is the go version. I upgraded from 1.13 to 1.21.