The currently Edge's Dark Theme, for Android version deson't sync with the system theme. Since Android Pie (On Samsung) and now, with Android 10, I can turn on the dark theme on Android and define a lot of apps to dark too, but it doesn't work with Edge. Please, add the API for turn on or turn off the Edge dark theme with system.
Updating the Chromium version to 76, I think the Edge for Android also can change the page background using the setted setting of themes, like is on Edge Insider on Windows. I'd love if you do it.
Another problem is with passwords. Currently my passwords are on Edge Insider and Edge for Android, but if I try to sign-in in an app, like Netflix, Instagram etc, I need to type my password again, or save it on the Google Smart Lock. I don't want the Google save my password, so I think the Microsoft shold create a app or become the Edge compatible with Autofill's APIs of Android, like Google with SmartLock or Mozilla, with LockWise.
And the last thing is a bug that I found. When I'm watching a video, the screen doesn't stay always on. I need to be touching every moment for the screen doesn't turn off. This is boring too and I hope the Microsoft fix that on the next update.
