(@burnout426 Thank you, I also tried these)
It's funny. The problem only occurs with the default background, and light theme. Not with dark theme or other background images.

Thank you very much for your help.

@burnout426
No error with standalone install
Here is a picture of the error:
https://drive.google.com/file/d/1mtB9dijImkd00OmsbqkDq8F5fKejAH9z/view?usp=sharing

This bothers me a lot. I hope it will be fixed.