xdg-open doesn't respect $BROWSER for URLs

I expect $BROWSER to be respected by xdg-open,

% env | grep BROWSER
BROWSER=firefox

But it's not:

% xdg-open https://example.com
<opens in chromium>

This output from xdg-settings is evidence that the intention would be for browser to be respected before other settings:

% xdg-settings set default-web-browser firefox.desktop
xdg-settings: $BROWSER is set and can't be changed with xdg-settings

Here, xdg-settings implies that set default-web-browser should have no effect if $BROWSER is set, so it refuses to do anything. But that disagrees with xdg-open's actual behavior.

---

% uname -a
Linux pele 6.12.7-arch1-1 #1 SMP PREEMPT_DYNAMIC Fri, 27 Dec 2024 14:24:37 +0000 x86_64 GNU/Linux

% pacman -Qo =xdg-open
/usr/bin/xdg-open is owned by xdg-utils 1.2.1-1