Coincidentally, also the most complicated thing imaginable.
I don’t believe that would be referred to as “the proton” unless it was being called “the proton compatibility layer”. It’s important not to forget the colloquial meanings of words :)
people make grammatical mistakes often enough when typing that you kind of need to parse sentences in the way that makes the most sense. this sometimes means parsing correct grammar as a mistake because the fixed version makes perfect sense. then you read the article and laugh at yourself because yep, both kinds of proton are quite complicated.