FYI "all but impossible" usually means the opposite of what you think it means - "all but" meaning "everything except". Seen this usage a lot and it bothers me, because both usages are common and theyre the exact opposites.
If I didn't have context clues, it'd be difficult to know which one you mean.
If I didn't have context clues, it'd be difficult to know which one you mean.
Edit: not native but I've always understood it as the first def here https://idioms.thefreedictionary.com/all+but