Didn't spot this one in the domain list, but it seems steam is using cdn.cloudflare.steamstatic.com for a lot of their store page content as well as user avatars etc.
https://cdn.cloudflare.steamstatic.com/steam/apps/1091500/header.jpg?t=1607428743
https://cdn.cloudflare.steamstatic.com/steamcommunity/public/images/avatars/d5/d52743ced29f850a32112bf611c2120b38fc7c5d.jpg
Didn't spot this one in the domain list, but it seems steam is using
cdn.cloudflare.steamstatic.comfor a lot of their store page content as well as user avatars etc.