More info: the browser (Firefox) is copying it as public.utf-plain-text, but when Bear inspects the clipboard and sees a URL, it adds public.url and net.shinyfrog.bear.url-name to the pasteboard. When it sees [x]( or similar, it should fall back to plain text. Pasting with ⌥⇧⌘V is a workaround, but not ideal.
This sounds like a good improvement to the editor experience but might be very tricky to differentiate the paste for this particular scenario and leading to errors. I’ll keep note of this and we’ll discuss after Bear 2 release.