GNU Fortran (GCC) version 10.2.0 (x86_64-pc-cygwin) compiled by GNU C version 10.2.0, GMP version 6.2.0, MPFR version 4.1.0, MPC version 1.1.0, isl version isl-0.22.1-GMP warning: MPC header version 1.1.0 differs from library version 1.2.0.
Comment#0 is about a specific installation. Please report to the Cygwin people.