https://bugzilla.redhat.com/show_bug.cgi?id=1839256
--- Comment #6 from Robert-André Mauchin zebob.m@gmail.com --- Should rather be
%files -n mingw32-python3-%{pkgname} %{mingw32_python3_sitearch}/cv2-cpython-%{mingw32_python3_version_nodots}.dll
and
%files -n mingw64-python3-%{pkgname} %{mingw64_python3_sitearch}/cv2-cpython-%{mingw64_python3_version_nodots}.dll
I've sent a PR to mingw-python3 to add these macros: https://src.fedoraproject.org/rpms/mingw-python3/pull-request/1