I don’t know why the field there has “Private owner” written in it but it’s a United Kingdom - Royal Air Force (RAF) fighter jet.

Google has tons of hits for ‘Eurofighter ZK378’ with lots of pictures.

In that construction number list, it’s also listed with the UK Air Force. https://www.spottingmode.com/eurofighter_ef.2000_typhoon/cn/rundown/100/

Another site (the credibility of which I don’t know) says it’s RAF.

Sometimes they say that for some reason. Likely not privately owned, I’ve seen jets like these marked “Private owner” fly w/ RAF.