I think the point is that it’s not showing up on the standard financial filings. If you were to pull the annual reports for these companies, you wouldn’t see it. That doesn’t mean it’s impossible to find it. Obviously, it is otherwise the article wouldn’t have been written. But you’re going to have to go the extra mile. To be clear, none of this is illegal. It’s just covered in the advanced CFO accounting class.
Take-or-pay contracts appear as "contractual commitments" in 10-K. They are not hidden. That's the way they are reported in all industries where take-or-pay contracts exist. There's nothing nefarious about it.
It's not hidden at all. Financial blogs very accessible to laymen like Matt Levine's Money Stuff have talked about this structure months ago. If you are an investor and surprised by this news you weren't sufficiently prepared and shouldn't have been investing in the first place.