Same problem from v. 80.0 is back in 82.0 to current 83.0
I posted this problem back when v.80.0 was out. It was later fixed, but now it's back.
Loading an external bookmark as the default start page in v.83.0 and using it as the default bookmark (file:///C:/Mine/Testing/BOOKMARK.HTM) creates an error.
The error is that clicking on any url in the bookmark to visit and then clicking the top left arrow to return will always bring you to the top of the bookmark. It used to bring you back to the same location on the bookmark. Now, it brings you back to the top of the bookmark. Thus making it necessary to scroll back down to the location (url) you just visited. Really annoying to have to keep do this in order to return to your original location in the bookmark.
Hope someone can help again.
jscher2000 (jscher2000) helped and filed a bug report back then....... https://bugzilla.mozilla.org/show_bug.cgi?id=1636364