In both array-api-extra and scipy, the xp fixture depends on monkeypatch, as required by lazy_xp_function.
This in turn causes pytest-run-parallel to automatically disable parallel testing for all tests that use xp, for all backends, including when SCIPY_ARRAY_API is not set.
Desired behaviour
Thread parallelization should exclusively be disabled for those backends that actually require patching, which means JAX and Dask.