libSystem.dylib not found

Hello,
When linking with gfortran, libSystem.dylib is not found (either in /usr/lib or /usr/local/lib)
I have xcode and command-line tools 12.3 version.

Previously, with version 12.2, I was able to compile with gfortran (with gcc reinstall).
I would greatly appreciate any help to solve this issue.
Thanks

My Config is:
Mac OS: BigSur 11.1
bash-3.2$ gcc -v
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/4.2.1
Apple clang version 12.0.0 (clang-1200.0.32.28)
Target: x8664-apple-darwin20.2.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
bash-3.2$ gfortean -v
bash: gfortean: command not found
bash-3.2$ gfortran -v
Using built-in specs.
COLLECT
GCC=gfortran
COLLECTLTOWRAPPER=/usr/local/Cellar/gcc/10.2.0/libexec/gcc/x8664-apple-darwin20/10.2.0/lto-wrapper
Target: x86
64-apple-darwin20
Configured with: ../configure --build=x86_64-apple-darwin20 --prefix=/usr/local/Cellar/gcc/10.2.0 --libdir=/usr/local/Cellar/gcc/10.2.0/lib/gcc/10 --disable-nls --enable-checking=release --enable-languages=c,c,objc,obj-c,fortran --program-suffix=-10 --with-gmp=/usr/local/opt/gmp --with-mpfr=/usr/local/opt/mpfr --with-mpc=/usr/local/opt/libmpc --with-isl=/usr/local/opt/isl --with-system-zlib --with-pkgversion='Homebrew GCC 10.2.0' --with-bugurl=https://github.com/Homebrew/homebrew-core/issues --disable-multilib --with-native-system-header-dir=/usr/include --with-sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX11.0.sdk SED=/usr/bin/sed
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 10.2.0 (Homebrew GCC 10.2.0) 


I installed gfortran from HPC Mac OSX
There is still a reference to libSystem and libm at link stage, but it succeeds to build an executable (which runs perfectly).
Issue tackled, but I don't understand the root cause.
libSystem.dylib not found
 
 
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