I am not sure why is not expected to work nicely on desktop (mobile-view) and mobile (desktop-view). This is a little bit edge case I know, but on desktop (mobile-view) would be nice if for no other reason, but at least for dev purpose. If we switch to mobile view then we should see almost the same like on a mobile device without simulate it on virtual device.
On the mobile (desktop-view) now overflows the modal content. This is also an edge case but sometimes Discourse detects wrongly the mobile devices browser so it drop them to desktop-view.
I have no immediate answer or solution for it unfortunately. And since this is something that transcends this particular topic, I’d recommend opening a dedicated topic if you feel strongly about it.