I wrote a simple test program to better see the differences between Linux (glibc) and Windows (MSVCRT).
Which windows version did you try? Windows 10, 11, olde? Sigh!!!
Good ol' Windows 7. I will never use anything newer.
Switching to GLib DateTime API should be fairly easy, I'm only wondering if this might break other format specfifiers.
#3037 is there and has information about missing format conversions.