I’ll stand corrected. I’m not a native English speaker and when I saw “can not” it immediately reminded me of my school teacher in Europe who was very particular about these things and teaching us as wrong. Even as I typed my response now my iPhone tries to autocorrect it to cannot, so I genuinely thought it was wrong. TIL I guess.
“Both cannot and can not are perfectly fine, but cannot is far more common” [1]
[1] https://www.merriam-webster.com/grammar/cannot-vs-can-not-is...