The whole north-south language divide is so obvious in hindsight yet it never crossed my mind before lmao.
In Vietnamese there's this big divide between northern and southern dialects, not just the accent, maybe it's like that in Chinese
Father and mother is "bố" and "mẹ" in the North, "ba" and "má" in the South. Pig is "lợn" in the North and "heo" in the South. Fruits and dishes have different names. Insults also vary. Thus, it's quite easy to ascertain someone's hometown just looking at their written words.
Suddenly using words not from your regional lexicon is either strange (like Tang Mengji), or, if you're still young, very hilarious. My 10-year-old self once called an amona "quả na" (Northern term) instead of "quả mãng cầu" (Southern term) and got some funny looks from my central-southern family.