This is because DisplayLink uses screen sharing technology to output images to an external monitor, and streaming videos (Netflix, Disney+, HBO max, Amazon Prime) have copyright protection, so they cannot be played normally when sharing the screen.
This problem can be solved like this:
1. Use Google Chrome.
2. Turn off hardware acceleration in Google Chrome. Refer to this link
Then you can watch streaming videos (Netflix, Disney+, HBO max, Amazon Prime) in Google Chrome.