I noticed that the "Fedivers Reactions" Blog from Activity Pub Plugin loads the user avatars uncompressed.
There are quite big filesizes like 221kb for an avatar. The more people like a blogpost, the more Co2 it will emit. :blobcatcoffee:
I opened a support thread about it: https://wordpress.org/support/topic/fediverse-reaction-block-loads-huge-images/