Comment by danielcid

Mostly because of sub domains. They are counting all the sub domains requests to give the top domains ranking.

Some of those have many trackers and background sub domains that add up.

For example, Linkedin their most popular sub domain is: px.ads.linkedin.com

Here is a more comprehensive list with top 10k domains (including sub domains):

https://dnsarchive.net/top-domains?rank=top10k