It’s technically problematic. The ISP should have little idea of domains you visit. And they can’t already when everything works.

Plenty of ISPs zero rate things like Facebook and other "partners". Especially easy when they control the DNS.

Do you have heared of IP addresses and that large institutions especially government institutions have their own blocks from the address space? Mapping these is kind of easy.

They are likely behind (foreign) CDN's.

Not that there's no BYOIP and not that it's impossible to do with shared IP's