Every language seems to have some quirk that makes it non-trivial even for adult native speakers. For English it's knowing how to pronounce a word based on its written form and vice versa, for Polish it's partially actually pronouncing it but even more so a ridiculous amount of grammar and orthographic rules and exceptions, and for Japanese it's the thousands of Kanji characters, some of which are used rarely by people wanting to be extra fancy.
What's that thing in other languages? Summoning @thor for Norwegian.
@Amikke it's not unique to Norwegian and is also true of German, but: needing to know the gender of every noun.
the "genders" don't mean anything but the linguists call it "gender"
you just have to remember which of 3 belongs to word X.
@Amikke i will say Ø and their lips struggle to say it, for example. it's very rare that foreigners manage to speak it without a thick accent unless they're from a German or Dutch speaking area. they seem to have an easier time with it.
@Amikke i don't keep a list of quirks. i just get reminded of them periodically. but i'm always surprised at how hard people find it to pronounce my language. i will say a simple word and they'll repeat it wrong.