I'd rather they mandate uniform unit-volume price labeling. This feels like micromanaging.
This does feel a little like micromanaging but it does seem good. If someone buys the same product every week for 10 years, they're -never- going to be on the lookout for "has this product changed this week, is it smaller now?".
(1) of course within limits suitable for our household. It doesn't make sense to buy stuff the won't be consumed before it's getting unusable.
In the very old days in Germany chocolate was only allowed to sold in certain fixed sizes. 100 grams bars had >98% market share, although several other standardized sizes were allowed, too. With EU free markets that regulation had to be abandoned because it hindered free market access. I don't know whether unit price information was introduced at the same point in time, I wasn't living there at that time. But I still hate to see 90 grams and 282 grams chocolate bars where I live now.
However it's not much useful to combat shrinkflation because if, let's say, icecreams shrink maybe you realize it only when you open the box at home and you get the feeling that something changed. Or if you notice that a pack of food that has always been 500 g is now 450 g. You can't remember with precision the old price per kg but you definitely suspect that the manufacturer is playing the shrinkflation game.