qt.qpa.xcb: could not connect to display qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/root/anaconda3/envs/DCGAN_tf/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. Available platform plugins are: xcb.

[yanweijia-1]

[ea-evdokimov]

You can try downgrade opencv, for example pip install opencv-contrib-python==4.1.2.30, it helped me