I suspect (but cannot prove) that this might have been a leak from Russia's internal internet into the wider global net. Since Russia isn't well known for it's privacy respecting nature, it might have been a traffic scanner to see if people are being good citizens. However, that is just speculation and I hope it's wrong.
Maybe they were testing effective ways to block foreign sites?
Yes, indeed! Guilty until proven guilty! Keep up the upstanding attitude, good citizen!
https://arstechnica.com/information-technology/2010/11/how-c...
For ECDHE over P-256, they would need to wait for a big quantum computer (which will break all recorded traffic that used a non-quantum resistant key exchange, which is all current traffic).
But as we all know, NSA does store all traffic for future analysis. A BGP leak from China or Russia, be that as it may, almost surely has nothing to do with storing traffic.
{{Citation needed}}
It's possible and easy, the list of ciphers in the ClientHello is different. Take a look at https://www.ssllabs.com/ssltest/clients.html to see what several popular browsers look like.