I use uv@0.4.0 to pip compile the dependency specifier scipy==1.9.0.
scipy==1.9.0 has a Python version requirement of >=3.8,<3.12.

The command I'm running is
echo "scipy==1.9.0" | uv pip compile --python X.Y --python-version X.Y [--universal] -

When the command fails, the error message is always:

  × No solution found when resolving dependencies:
  ╰─▶ Because the current Python version (3.12.5) does not satisfy Python>=3.8,<3.12 and scipy==1.9.0 depends on Python>=3.8,<3.12, we can
      conclude that scipy==1.9.0 cannot be used.
      And because you require scipy==1.9.0, we can conclude that your requirements are unsatisfiable.

I've compiled a table of results with different combinations of --python and --python-version arguments + --universal mode.

There are two failures that definitely look unexpected to me.
I'm not certain whether --python 3.11 --python-version 3.12 --universal is expected to succeed.
Also, I had the impression that python version upper bounds were ignored (in --universal mode?), so maybe some of the cases I marked as expected failures are actually unexpected.