This seems bad for 'stablecoins' given yield at a minimum offsets the real purchasing power loss due to inflation 

More like unstablecoins

It's called narrow banking. Matt Levine has discussed it in his newsletter few times.

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Makes sense if tradfis also become narrow banks across all their liquid assets: cash and stablecoins

But if it's just the stablecoin part then it's pure extractive greed on the issuers part, who no doubt lobbied for something like this to be included in the Act