Old Edge let you swipe back and forward with a very short motion, but this new Edge require swiping almost across half of the screen.... That means it requires having to use a free hand. With old Edge it was possible to do these swipes with just your thumb while holding the side of the screen, much easier/faster/convenient/natural/better ;)
Chromium 75 has #overscroll-start-threshold in chrome://flags or edge://flags. This must've been removed recently. You should consider checking Chrome Canary (to see if Edge or Chromium made the change) and then make a Chromium issue. :)
I found Edge Spartan's behaviour very annoying while scrolling but that's just me.