The Latest Microsoft Edge Canary build 86.0.572.0 no longer contains the “Customize browser” section in Appearance settings, which means, you can no longer change the Edge browser theme to light or dark and you can’t set a preferred Zoom level for web pages in the browser. Microsoft is aware of this issue.

Microsoft Edge by default follows Windows/Mac System theme, but allows users to change browser theme to light or dark by visiting settings > Appearance > customize browser > Default theme.
For instance, if you’ve set Windows 10 default app mode to dark, you can select the ‘Light’ theme for Edge from Appearance Settings.
Similarly, if you set Windows 10 app mode to Light, you can make Edge look darker by selecting the ‘Dark’ in the Default theme setting, this no longer possible now.
Microsoft Edge Canary has lost the Zoom setting as well. Edge Dev not affected and here is how the appearance Settings page should be in Canary.

Microsoft acknowledged the issue and said the Edge team is working on it.
“Great news: this is a known issue in the Settings page, and our team is already working on it!” says Microsoft.
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