This clever pricing system is only available on Itch.io, [...] It is also on sale on Steam until March 7, but that price doesn't fluctuate.
I thought steam had some sort of t&c agreement where you had to price all copies of a game the same no matter the store they were on. surely this would violate those rules. or am I misremembering that?
It would, but Steam only kind of enforces the rule. They seem to enforce the rule if there is a significant and constant history of pricing a game lower on another platform (eg Humble Bundle)