In Japan, I don’t recognize words and expressions that normal people know.
Sometimes there are words and expressions that feel specialized or uncommon to me, but those around me respond with, “What? You don’t know this?” My parents and younger brother also teased me about this. After becoming a working adult, people would also point out that, “Your particles are a little off.” I run into things like this during conversations, and when I’m not familiar with a word and ask something along the lines of, “What’s that, something from your dialect?” they’d respond with, “What? It’s not a dialect thing!” But it was still so out of the blue to me, and I couldn’t recognize it at all.
Regarding the written word, after beginning to work I asked people to, “Tell me if my Japanese is odd,” so sometimes they’d point things out. I was told that my particles and word ordering are “English-like.” For example, when I use words like “all,” or “basically,” my placement for them in my sentences is apparently completely like English.
I guess it’s alright in the end, because everyone would say, “Oh, it’s because she’s a returnee,” and laugh it off.