deutschtaeglich:

My mind has been blown: cats only have 7 lives in German! (They have 9 in English!!)

…because German is just that much harder to learn.

I suspect that a contributing factor is that because in German, the word for “lives” is “Leben”, and the German number that most closely forms at least an imperfect rhyme with Leben is sieben (seven).

Katzen haben sieben Leben.