nostr:npub1hxlun7ekul082xz0zyn0dkdc5226sxctuug5dzr38mztsprqg0lqfm0f4h 

Without inside information it would be tough. If you had long term data you might be able to get some results from http responses or ping times but that would be measuring symptoms. 

Many moons ago when I worked in public service, we were the targets of a persistent ddos. They almost took us down -but only almost- so we didn't even acknowledge the attempt.