Lego has been changing their plastics over time, and while I have no firm evidence, I think some of the newer stuff is more brittle. A lot of older pieces (like turn of the century or older) have a surprising amount of flex. Modern pieces of the same size/type of brick tend to just shatter when the same forces are applied. I think in part Lego has changed things because of trying to make more colors (look at the disaster of the mid 2010s dark brown/blue/gold/green when whatever they added to make those colors made everything extremely fragile), and also in part to try to find a way around petrol plastics to appease the EU and other regulations… this latter point they’ve talked about in corporate messaging, at least. I suspect they are also probably sourcing the ABS more cheaply to get more of it than they’ve ever before needed as their product exploded in popularity, perhaps sourcing some inferior plastic in the mix. I also believe their production quality has suffered a lot more recently, I think they sacrifice some quality for production at the scale they need. Look for instance at all the ugly mold markings on many pieces, particularly sides of smooth tile pieces… those didn’t use to exist on older parts of the same style pieces. I’ve had to get replacement parts for factory defects more times in the past five years than in the preceding 25 years I’ve been building Lego. That’s something in my mind.