Steam’s policy is to, if a gamedev company gets a better offer in another store that doesn’t add the 30% markup that Steam adds to the price of games and shares that with their customers by selling their games cheaper in the other store, Steam will take their games down from the Steam store.

Does anyone have a source on that? I couldn’t find that clause in their docs, all I could find that is in this: https://partner.steamgames.com/doc/features/keys

You should use Steam Keys to sell your game on other stores in a similar way to how you sell your game on Steam. It is important that you don’t give Steam customers a worse deal than Steam Key purchasers. (…) It’s OK to run a discount for Steam Keys on different stores at different times as long as you plan to give a comparable offer to Steam customers within a reasonable amount of time.

To me, that reads that this is only about selling steam copies of the game on other storefronts (like humblebundle for example), developers are free to sell non-steam copies of the game on other storefronts (like GOG or epic) for cheaper.