Does Airtel block TLS 1.3 with the encrypted SNI extension enabled? https://blog.cloudflare.com/encrypted-sni/
But Airtel really, really wants to run scripts and show ads on blocked pages.
Duckduckgo - https://i.postimg.cc/SqkRhpRC/Mozilla-Firefox-29-09-20-w-PA....
Pirate Bay - https://i.postimg.cc/qMmwMXVY/t-29-09-20-9-Dv.png