Chiming in as an instance admin. The larger the instance the slower federation becomes as it has to send the data to every instance that it federates with, if you’re a small instance just starting out federating with Lemmy.world for example is extremely slow as you’re essentially last in line to receive any data.

I have also noticed holes in federation, for instance a community I created !ca_firearms_rights@lemmy.halstead.host federates with sh.itjust.works fine but not Lemmy.world (haven’t figured out why).

Give it time, hopefully correct itself.