pyqt5-tools pip install crashes Qgis 'couldn't load sip module. Python support will be disabled'

[hcroope]

Hopefully this is the 'correct' place to post this.

I pip downloaded (with my conf: python -m pip install pyqt5-tools) pyqt5-tools (using Qgis 3.10.10 and 3.10.7 Coruña) and it seems to cause Qgis to crash while starting up python ('couldn't load sip module. Python support will be disabled'). Fastest fix I managed to find was just to reinstall Qgis. Some background: I'm using python that came with Qgis by copying 'python-qgis-ltr.bat' to 'python.bat' (in /bin) and adding bin path to PATH. Also, downloading pyqt5-tools to use QtLinquistic and pylupdate5 path/translate.pro AND lrelease path/file_lang.ts

The SIP subroutine could not be loaded.
Python support is not available.
...
  from PyQt5.QtCore import *
ImportError: DLL load failed: The specified procedure cannot be found.

*translator used

[JonB]

@hcroope
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