Why do I have different IPs when connecting to different sites? Provider proxy?

Question

Computer networks

Screenshots of four different whois

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This is a local monopoly provider.
When refreshing a page with clearing cookies, the IP remains the same for a particular site, and different for different ones.

1. Why do I have different IPs when connecting to different sites, while each site has its own IP, and it doesn’t change there?
2. Why does the provider do this?
3. Is there any mechanism to force the change of the external IP for this particular site, except for the proxy?

UPD If you have something to add to the answers below - write!

Answer 1

Most likely, the provider has several channels and load balancing is configured, so a new connection can go along a new route with a new ip.