WARNING Thread(Thread-3 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser

Using:
Python 3.11
Multiprocessing
Kaleido 1.0.0rc13
choreographer 1.0.7
plotly 6.1.0
venv

I have a script which using multiprocessing (limited to 30 cores right now on this machine), to generate lots of static images for hosting. I've just moved to testing the new plotly with the new kaleido (another long suffering W11 kaleido hanging process user here), but discovered a new problem so flagging it here because I've not seen it raised anywhere else.

My logs are full of:

WARNING Thread(Thread-3 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-3 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-3 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-3 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-3 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-3 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-3 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-5 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-5 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-5 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-5 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-7 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-7 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.
WARNING Thread(Thread-7 (run)) choreographer.browser_async:browser_async.py:_close()- Resorting to unclean kill browser.

I've not seen anyone post this. I'm attempting to put a small script together to reproduce this out of the venv in which it current runs to remove that.

Is it a known problem? Can I suppress the warning if that's all it is? Do I need to care?

Start with choreographer/browser_async.py, especially the _close() path named in the warning, and review how browser shutdown behaves when multiprocessing creates many workers. Build the promised minimal reproduction using Python 3.11 and the listed Kaleido, choreographer, and Plotly versions. Done means identifying whether the warning indicates a real cleanup failure and documenting or testing the appropriate behavior.