In June 2022, Microsoft released an Edge update with significantly upgraded visuals. A new experimental flag made it possible to turn on the Mica effect on the tab strip and toolbars for much better looks on Windows 11. Fast forward to January 2023, and the flag responsible for turning on the eye candy is gone.
As spotted by @Leopeva64, the latest Edge 111 Canary update has removed the “Show Windows 11 visual effects in title bar and toolbar” flag, making it impossible to turn on the “Show Windows 11 visual effects in title bar and toolbar (Preview)” option in the browser’s appearance setting. Now the tab strip, toolbars, and sidebar use the default dull-looking gray background (or another non-translucent color you have set in the settings). Fortunately, the flag and setting are still present in Edge Stable.
There is no information on why Microsoft has removed the Mica effect from its browser in the Canary Channel. Also, this is not the first time the company deleted visual upgrades from Edge. Perhaps, Microsoft is working on a better variant, which might be a part of the rumored Edge “Phoenix”—a reimagined version of the browser. One can also guess it is a temporary change or bug that Microsoft will revert.
We will update the article once we have word from Microsoft.