A lot of ingredients have changed.
In particular, I once followed a recipe for hot chocolate that included evaporated milk, only to discover that modern evaporated milk has half the water content of the original product.
It came out like chocolate cream, very sweet. Everyone loved the thickness of the drink, but we could not handle the sweetness.
If you order hot chocolate in Italy today, you will get that same wonderful chocolate cream.
Eggs seem smaller also. I’ve learned that for old recipes, if I want them to turn out the way I’d planned, I have to substitute jumbo eggs for large or extra-large, and large for medium or small. JMO.
And don’t even get me started on CREAM, LOL!