I had facing a font issue for a long time, and finally figure it out these day. When websites using icon fonts as a element, my edge, which has a default font set in Setting>Appearance>Font, won't display them. It will become a square, some random character or nothing. I will give some screenshot about that.
It turn out that when you set a default font, edge just set a base font and give it a !important in the css. I try to delete this !important, and it solve the problem.
However, simply delete the !important will make your font setting no functional. It seems that edge try to use selector to avoid this situation, but it can't cover many websites, even websites form the same company (Screenshot is Microsoft Learn). I wish developers can fix this selector, or give users a place to add their selector when facing this issue.
This issue should be platform independent. I had try all latest versions of edge insiders and stable release on Linux, and stable release on windows. I can't use my windows PC these days, so I can't try windows' insider version.
Just set your own font and visit some websites using icon fonts, like Microsoft Learn.
Finally, as a temp solution, how can I restore this setting to default? The only way I found is create a new profile, but it will take a long time to config again.
Apologize for my pool English and broken grammar, and thanks for edge developers' work on this browser and your efforts to port it to Linux platform.