The weirdest experience I’ve had with language mixups so far is that my brain apparently seems to conflate anything not English. English is my first language, and I used to be able to speak German pretty well — not fluently, but well enough to hold a fairly natural conversation. I have unfortunately let it slip away now. I’m now learning a different language and for some reason whenever I don’t know a word for something but I do remember the German one, my brain just picks the German one. It’s quite frustrating.