What is the issue with the Quirks Mode Standard?

There's a longstanding list-style-position quirky behavior that browsers have to varying degrees, where they set list-style-position: inside (instead of the initial outside value) on bare li elements (those with no ul parent node) under certain conditions.

In Firefox, this quirk is fairly limited, and it lives here in the quirks-mode UA stylesheet.
https://searchfox.org/mozilla-central/rev/0b1543e85d13c30a13c57e959ce9815a3f0fa1d3/layout/style/res/quirk.css#8-23
(Since it's in the UA stylesheet, the effects of this behavior are shown in the computed styles, and authors can override it if they want.)

For a long time, Chrome and Safari have had a different & broader version of this behavior that's (a) not quirks-mode specific and (b) not overridable by authors; more details/investigation in https://bugzilla.mozilla.org/show_bug.cgi?id=1799724 . But I think they're moving away from that -- WebKit trunk recently aligned with Firefox on the approach here (and that's already in Safari TP, though this change hasn't made it to a Safari official release yet). And I suspect/hope Chromium will change soon as well (maybe here based on current discussion on web-platform-tests/interop#857 (where it sounds like the use-counter's results make this uncontroversial).

So: given the browser alignment here, we should probably specify the quirks-mode-specific behavior that we seem to be aligning on; then we can add WPT tests about the quirky behavior that reference this spec text.