For Firefox, this may occur when the address bar autocompletes from history, pulling the https:// https:// entry. As far as I can tell, it doesn’t have anything

For Firefox, this may occur when the address bar autocompletes from history, pulling the https:// https:// entry. As far as I can tell, it doesn’t have anything to do with prioritizing HTTPS, just whichever is more frequent in your history (if you visit the HTTP enough times it will switch to picking that for autocomplete). If you don’t use the autocomplete entry (for example, by tab-completing it but deleting the trailing slash), then it will use HTTP unless you actually typed https:// https://.