I see that there are several requests on this topic, but they are not taken into account.The world complains about Microsoft that it is not responsive to what the users ask for, but look at how Mozilla ignores it.
In relevant browsers, the back button (or swipe back) returns to the previous page or, if it is the first page, closes it. This saves a lot of time, which is why it is implemented like this in most of them.I don't know why you want to block this func...