Edit: Looks like you can opt-out of that "new look and feel" pretty easily under the appearance settings but still, whats with putting rounded corners everywhere?
Edit 2: "Explore the web with a softer, more friendly aesthetic featuring rounded corners […] Designed to complement your operating system, whether on Windows 11, MacOS, or Linux." The fuck does that mean? Windows 11 fair enough but most Linux distros don't look like that at all.
Not being open source ≠ not safe.
Microsoft ships hardened Chromium basically, with sandboxing turned up to eleven.
They also run their SmartScreen filtering on top of that.
Also, Firefox is more private, not secure. Either you run LibreFox or it’s less secure than Edge by default.