The vast majority of reputable sources that appear via search engine say that alright is the informal version and all right is the formal version.

Let's say that the latter is indeed an overcorrection and alright is the correct version; is the first syllable not actually referring to the notion of everything i.e. all -- it's some other prefix?

A common mistake I see: Every day is two words, everyday is strictly an adjective e.g. an everyday occurrence.