No, it's not collusion to ask for more money from OpenAI if you hear that they are trying to buy 40% of the world's supply. Increased demand leads to higher prices, that's normal.

OpenAI, by doing simultaneous deals, hid the true demand from the suppliers, thus lowering their price and raising everyone else's.

Every normal market interaction could be described by scary monopoly-sounding words. You heard about you're friend's salary in the same industry, and ask for a higher salary next time you negotiate. You're colluding with your friend to price gouge your employer!

In reality, so-called collusion is normal and unobjectionable. But when price surges happen, often due to factors outside of the seller's immediate control, people look for any reason to find an ethical dimension and find how to place blame, because this is more convenient. Things that were normal become abnormal and suspicious. It is in consumers economic self-interest to act in this way, because it often secures favors to them from various economic policies that they don't normally get when the market is "normal". This is no less a form of collusion than what sellers might do to secure their economic advantage. But a key difference for these anti "gouging" policies is that it gives consumers a special privilege and makes market pricing less able to fulfill its social functions.

They have, rather famously, been caught doing financial shenanigans before. [0]

[0]: https://en.wikipedia.org/wiki/DRAM_price_fixing_scandal

A competitive auction would not be collusion.