User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:70.0) Gecko/20100101 Firefox/70.0
Steps to reproduce:
I entered the first letter of a frequently visited website, which contains a subdomain (e.g. board.topic.com).
The Addressbar doesn't autocomplete the URL, unless
browser.urlbar.suggest.bookmark is set to true. Crucially, this applies to URLs whose domains are not bookmarked.
The Addressbar should expand my entry to the URL of the most visited site, at least if the visiting frequency stands out by a large margin. This behavior should not be dependent on aforementioned "bookmarks" toggle, as the two are functionally independent concepts.