those are CNAME’d domains. some ad networks use them to get around basic DNS blocking but a vast majority of them are for innocent tech reasons usually due to cloud scaling infra (think CDNs and whatnot)

the little text underneath shows what domain your browser’s connecting to, and the large text is what the CNAME record is redirecting to.

I think that’s just how they show subdomains, and it’s related to Uncloak canonical names setting.