That is a good step forward. I checked with curl and got “Cache-Control: max-age=31536000, public, immutable” for that icon.
Filing issues is on my todo list.
I noticed two days ago that Aurora Droid has changed its configuration for the F-Droid repo. They now use F-Droid as the default mirror instead of F-Droid. This change likely took a significant load off the servers.