I had an interesting experience the other day. I have been using split keyboards for years, but only recently began using a Kinesis Advantage 360 Pro as my daily driver for work; I am so use to the layout now, that in instances where I have to use a non-split, or even my older splits, my fingers fail me entirely - like my brain forgot how to type, my thumbs eagerly searching for the thumb cluster that isn’t there.
Aside from the forced wrist pronation of standard keyboards, it’s always the pesky square brackets and parenthesis that mess with me when I switch.