Probably influenced by the most popular JavaScript library for achieving this type of layout, Masonry[0]. The author notes at the end of the article:
> But do expect the name of this value to change in the future. And perhaps prepare for a future where we call this “columnar grid” or “Grid Level 3” instead of “Masonry”.
I expect this is the case, if I had to describe that layout in iOS-land I'd also call it "masonry".
It's a pretty common descriptor in the Wordpress world - grids/scrapbooks will often have masonry as one of their layout styles. Maybe 100 years from now when people are browsing in their neurodisplay they'll be able to think "masonry" and have their photos tile the way they like, never having heard of Javascript or CSS in their lives. Language is neat like that.
> But do expect the name of this value to change in the future. And perhaps prepare for a future where we call this “columnar grid” or “Grid Level 3” instead of “Masonry”.
[0] https://masonry.desandro.com/