I was installing a broken plugin (an adaptation of the spectrometer plugin) which I am trying to debug. Would not be surprised that this was the main cause. After that I got issues with the public ssh keys. This was could be reverted by downgrading the pi imager. A fun afternoon 
This is such an annoying bug! I am very frustrated that RPi has completely turned a blind eye to fixing it too =\
Does your spectrometer plugin fork have a dependency on numpy somewhere? This can be a problem, if so.
You might have to uninstall pip-installed numpy, like so:
sudo pip uninstall numpy
and then see if it works.
Thank you Cameraon. That solved the issue. My guess is that while installing the AS7341 manually, numpy was installed.
Possibly!
We have a better python library management update coming, which should avoid these issues in the future.
Thank you Cameron. The error reappeared. Installing the numerical libraries fixed it (for now):
sudo apt-get update
sudo apt-get install -y libopenblas0-pthread liblapack3
Hopeffuly won’t break something else further down the line 