I have a smal knowledge of Tor, but could this be an attack to uncover sources?
For example, let’s say a nation state controlled a large number of exit nodes (10%), and then DDOSed the other legitimate 90%. Would this force all traffic to the 10% they controlled?
Yes! Targeted DoS is one way to force traffic to your evil exit node, and also to attack onion service anonymity (by forcing the service to choose a new guard).
The 10/90 attack you're describing is probably not feasible due to monitoring by the network team. Those remaining unaffected nodes would be easy to spot as malicious relays and get removed from the netwotk.
It would not surprise me if nation states did control 10% of exit nodes. Onion routing however, means that exit nodes alone can not deduce sources. An attacker would need to control a whole chain to know both traffic source and destination, and the most important aspect of Tor architecture is to make that as difficult as possible.
For example, let’s say a nation state controlled a large number of exit nodes (10%), and then DDOSed the other legitimate 90%. Would this force all traffic to the 10% they controlled?