Ah, one of the bugs with Slate was with spell-checking. On mobile Safari, at least, its text nodes aren’t marked by spell check unless they’re interacted with by the user after they’ve been typed.
As I’d said, they all have bugs, including ProseMirror. I just found that PM solved most of the ones I cared about relatively well.
Last I evaluated them, they had some bugs that wouldn’t work for my use case. For example, Quill has the annoying bug on mobile Safari of blocking the native behavior of capitalizing the first letter of a new line.
I don’t remember what I found in Slate, however, and it’s possible it may be much better now.
As I’d said, they all have bugs, including ProseMirror. I just found that PM solved most of the ones I cared about relatively well.