I've already started seeing a lot of redundant communities being made here that have already existed on other Lemmy instances, and lemmy.ml is at risk of centralization and overload, so now is a great time to raise awareness of other instances.

For science topics, mander.xyz has a lot of good ones set up, and !solarpunk@slrpnk.net on slrpnk.net has been great!

edit: for new users - you can type ! to begin autofilling a community, even for ones on other instances, like I did for the solarpunk community above. It may take a few seconds for the autofill results to show up if you have a slow connection like me.