This video says (at 1:07) we cannot use "be going to" to describe future plans in a formal writing because its informal.
(I have already asked another question about an other claim of this video here.)
It contradicts my previous knowledge and also my research: link 1 link 2 link 3.
Is this claim correct?
A thought-provoking thing that I read was this sentence: "Be going to is commonly used in informal styles." in the Cambridge Dictionary. It does not say that "be going to" is not commonly used in formal styles, but it may indirectly imply and convey the feeling that it may not be a good choice in formal writing.
