Could not load the Qt platform plugin

[sadams207]

Expected behaviour

Application with matplotlib should be able to show a plot window.

Actual behaviour

Segmentation fault during the plotting process.
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/home/sadams/projects/meccanoFork/venv/lib/python3.8/site-packages/cv2/qt/plugins" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Steps to reproduce

• example code
  `import cv2
  import matplotlib.pyplot as plt
  import matplotlib
  import numpy as np

print(f'Build information: {cv2.getBuildInformation()}')
print(f'CV2 Version: {cv2.version}')
print(f'Matplotlib Version: {matplotlib.version}')
x = np.linspace(0,1,10)
plt.figure()
plt.plot(x)
plt.show()
`

See attached for build information.
Version control: 4.4.0-dirty
qt_debug.txt

Issue submission checklist

• [ X] This is not a generic OpenCV usage question (looking for help for coding, other usage questions, homework etc.)
• [ X] I have read the README of this repository and understand that this repository provides only an automated build toolchain for OpenCV Python packages (there is no actual OpenCV code here)
• [ IDK] The issue is related to the build scripts in this repository, to the pre-built binaries or is a feature request (such as "please enable this additional dependency")
• [ X] I'm using the latest version of opencv-python

[sadams207]

I realize that this is similar to IMShow No Window - 4.4.0.46 MacOS Big Sur #423;
however, this shows that it is not just Mac related.

[skvark]

Duplicate of #386 and #404.