As a Romanian who had to study German in school, I testify to that. I still remember the word "Umweltverschmutzung" but no idea if it's der, die, das, dem or des umweltverschmutzung :P

A small trick with the words ending in "-ung" is they're often feminine so "die" in nomanative.

I would have bet on "die", just coze it "sounds right".

If you are a guest, sentences like: "Wo ist der Verpackungsmüll?" And "Trennt ihr Biomüll?" Can definitely land you plus points

Everyone below 50 speaks B1 or better English anyhow.