I find myself a bit surprised that banks, increasingly often, have random transient bugs preventing login with #Firefox (usually, if you try some hours/days later, it works), while logging in with #GNOMEWeb works fine during that time.
As a result, I'm increasingly starting to add banking websites as Epiphany "web apps", just-in-case. It also lets me pre-set the downloads folder to the correct folder.
I'm glad this exists as an alternative when needed.