So I did this from Sweden with my ISP dns, Google DNS and Cloudflare DNS.
My ISP and Google resolved to 23.13.34.61, where Cloudflare resolved to 23.78.61.14.
The response times were 14ms vs 8ms. Cloudflare actually picked the faster one.
Even though iboth IPs are registered as US, the packets I sent clearly didn’t travel to the US.
I was able to visit horizon.tv without issues. However their API probably only accepts certain source IPs. Your source IP shouldn’t be affected unless you’re using Blokada Plus.