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.
Mozilla’s “Multi-Account Containers” extension on Firefox does a much better job at the multiple profiles feature you’ve described.
I miss the tab grouping from Chrome based browsers in Firefox.
And I think tab containers don’t provide the separation I need to properly separate work from private.