Even though triggered by a recent change in mc, this is not a bug in mc, rather a bug in the (ancient, unmaintained, Gtk2-based) libvte9 (vte-0.28).
See the upstream mc bug, as well as the other mc bug linked from there for explanation. Fix for libvte9 is at https://bugzilla.gnome.org/show_bug.cgi?id=729533#c6
