For completeness: I also disable all autocorrect/autocomplete on mobile because it's more trouble than it's worth, but I leave auto-capitalisation on. This is a thing, they're independent settings.

i absolutely HATE every automated keyboard-"helper", ever.

type in multiple languages constantly and all of these helpers constantly default to english usage. plus it would be weird to me if every sentence starts with a capital letter but the rest is left as it is. seems like such an arbitrary solution.