Naruto shippuden where do you look?

I watch on my amazon fire tv stick naruto shippuden i watched netflix but already with the 10 seasons where can i watch it now in japanese with german subtitles

https://www.crunchyroll.com/...-shippuden

Can it be that there's sometimes advertising?

Yes, if you watch without a subscription.

That's annoying why can't netflix just bring 21 seasons

Because Netflix can't do it "just" like that. Licenses can be expensive, especially with a popular series like Naruto. And for whatever reason, the rights owners may not want to offer Netflix the entire series right away.