Incomplete Web Page Loading

[sszxc]

Sometimes web pages may not load completely, icons will take up the entire width of the screen, and the styles of text will be lost, as shown in the figure below.

I am a beginner in front-end development and do not know how to accurately describe this phenomenon. Because this phenomenon is quite random, there is no reproducible method.

If possible, please give me some clues or debugging ideas. Thank you in advance!