[BUG]: Is this a bug?

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What version (or hash if on master) of pybind11 are you using?

2.10.0

Problem description

Not able to call Python embedded module from a C++ thread spawned from a Pybind11 module

I have a Pybind11 extension module with spawns multiple C++ threads. If the extension module is the Python thread A and a spawned C++ thread B, is there a way to import Pure Python modules in thread B?

It works when the same Python thread A calls imports and calls back into Python.
When the thread is B (C++), even though I have released the gil in thread A and acquired it in thread B, the import call silently fails.

Reproducible example code

No response

Is this a regression? Put the last known working version here if it is.

Not a regression

No source files, tests, or reproducible example are provided. Start by obtaining a minimal reproduction of importing a pure Python module from a C++ thread spawned by a pybind11 extension, including the thread and GIL setup; done means the behavior and supported resolution are documented or covered by a regression test.