I just tested this out using Gboard and it doesn't automatically add spacing after punctuation, at least not when typing regularly. If you use glide/swipe that might be the case, or perhaps if predictive words are used, but that's certainly something different and wouldn't (and doesn't seem to) apply to regular typing. Same seems to apply to SwiftKey.
I don't know how it works then but at least on Gboard it behaves differently compared to apple keyboard.I do use Glide Typing if it's available but normal typing too