These are the packages that would be merged, in order:

Calculating dependencies ...

!!! Problem resolving dependencies for =sci-geosciences/grass-8.4.1-r2
 done!
Dependency resolution took 0.83 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "=sci-geosciences/grass-8.4.1-r2" has unmet requirements.
- sci-geosciences/grass-8.4.1-r2::gentoo USE="X bzip2 nls opengl openmp png readline sqlite threads tiff truetype -blas -cxx -fftw -geos -lapack -mysql -netcdf -odbc -opencl -pdal -postgres -svm -zstd" PYTHON_SINGLE_TARGET="-python3_12 -python3_13"

  The following REQUIRED_USE flag constraints are unsatisfied:
    exactly-one-of ( python_single_target_python3_12 python_single_target_python3_13 )

  The above constraints are a subset of the following complete expression:
    exactly-one-of ( python_single_target_python3_12 python_single_target_python3_13 ) opengl? ( X ) pdal? ( cxx )