WhatIsMyIP.com shows that ASN 13335 has 960 IP ranges in 88 countries and belongs to Cloudflare. 104.18.3.125 is definitely in the USA based on this. There are IP ranges given for Thailand, but they are not even close! ASN Information for ASN 13335 - WhatIsMyIP.com®
ASN is a number assigned to a large network that serves a set of IP prefixes (subnetworks). What is an ASN?