In the same vein as your response, I’ve heard people say that they start dreaming in the other language, too, and understanding it. Being a monolinguist myself, I can’t speak with any authority, but my understanding is when you stop thinking about what you say and you’re just saying it, combined with the dreaming in it, is a good identifier.
People who say that they speak whatever random number of languages but it’s only memorized sayings…? Yeah, that’s not* the same thing, you guys.
Edit: I’m married to a Puerto Rican who works in interpretation and translation, just for my credentials here. In one of our last minor tiffs she did mention something about me not learning Spanish and how she felt some kind of way about it… but, hey. Languages are difficult, and there are plenty of relationships where a partner didn’t learn the language and it’s not a big deal. I’m busy and stressed out with work.
But, I want my Charmin Extra Soft toilet paper! Don’t you remember the bad days during the pandemic! Where Osama Kamala Biden didn’t protect us from price gouging and store runs!!