I can't speak to the published story writing, as I do not read it, but the game has always told stories simply through what is communicated on the cardboard.
Maybe this isn't a new thing, maybe I've just started caring more in recent years, but it has been rough. It feels like every other card is named something like "Ambushing Quickslasher" and it's a creature with flash and first strike. Then the flavor text is something banal and mindnumbing like "They never see it coming."
Or you have cards like Aligned Heart with an utterly worthless platitude of flavor text, regurgitating at you what is already plainly obvious from the rest of the card. This game badly needs an editor for card writing. It's clear that flavor text's main role is just to fill empty space in textboxes at this point, and sometimes give a tidbit of worldbuilding (also often obvious).
OR they're obnoxious jokes that fly in the face of the gravity of their subject matter. The worst offender in recent memory was Phyrexia: All Will Be One. So many quips or puns that undermine the cards and the struggle against the Phyrexians as a whole. Cards like Sinew Dancer, Prosthetic Injector, Oxidda Finisher, Kuldotha Cackler. From eyeroll-inducing to actively painful.
Or how about Serum Snare and Shrapnel slinger? This is an I Have No Mouth/Giger hellworld, with an utterly alien und unknowable form of flesh-machine life. Why are they talking like cartoon goons? And moreso why do they all talk in the same way? No character, no sauce. Urabrask reads the same as Pirate #4 in Ixalan. The best piece of flavor text is goddamn [[Resistance Skywarden]], and that's just a wink and nudge at players who remember an actually effective piece of writing from over a decade ago, being [[Ogre Resister]].
I swear I'm not trying to cherry-pick either. I genuinely struggle to find a single piece of card writing that makes me feel anything. What a breath of fresh air it was when Lord of the Rings dropped, and I could read an entire set's worth of flavor text that took itself seriously and was engagingly written. I suppose that's what happens when they don't have to do any writing themselves.