2x10^12 isn't crazy for a number of requests over 3 years.

For comparison Cloudflare deals with 32 million requests per second[0]. I don't know if they're at CF scale, but in itself it's still a plausible number for a multinational DNS.

[0] https://blog.cloudflare.com/application-security/

PS: mistaking the short scale for the longer is common, but that shouldn't be a pretext to straight throw every use of "billion" under the bus.