I checked my ONT today and saw that the IP was
100.111.159.242
They have finally rolled out CGNAT here (I checked with my neighbor) :\
They do have IPv6 but it's funky.
I can't use my wireguard VPN right now. I'll have to switch to IPv6 for that now. The thing is the firewall on the airtel ONT isn't flexible so either you have to disable it or enable. You can't allow specific ports.
And, IPv6 routing to cloudflare seems unreliable. It likes to route to POPs that are far away, Bangalore, Kolkatta etc.
While IPv4 nearly always prefers Mumbai (lower latency for me)
I'll try asking the support if they can do something about the CGNAT.