Looks like a DNSSEC issue, not a nameserver outage. Validating resolvers SERVFAIL on every .de name with EDE:
RRSIG with malformed signature found for a0d5d1p51kijsevll74k523htmq406bk.de/nsec3 (keytag=33834) dig +cd amazon.de @8.8.8.8 works, dig amazon.de @a.nic.de works. Zone data is intact, DENIC just published an RRSIG over an NSEC3 record that doesn't validate against ZSK 33834. Every validating resolver therefore refuses to answer.
Intermittency fits anycast: some [a-n].nic.de instances still serve the previous (good) signatures, so retries occasionally land on a healthy auth. Per DENIC's FAQ the .de ZSK rotates every 5 weeks via pre-publish, so this smells like a botched rollover.
I love how I work with IT for 20 years and don't understand a single acronym here other than DNSSEC
So a single configuration mistake in a single place wiped out external reachability of a major economy. It happened in the evening local time and should be fixable, modulo cache TTLs, by morning. This will limit the blast radius somewhat.
Still, at this level, brittle infrastructure is a political risk. The internet's famous "routing around damage" isn't quite working here. Should make for an interesting post mortem.