I noticed responding to posts in communities hosted at lemmy.ml gives the following warning:

This post is hosted on lemmy.ml which will ban you for saying anything negative about China, Russia or Putin. Tread carefully.

While I see where this is coming from and I agree with the general sentiment, I'm not sure it's a great idea to include such a message. I basically read it as an invitation to be off-topic and to derail conversations in order to annoy the admins. While it comes from a point of good intentions, it can be disheartening for the people running communities on Lemmy.ml to receive comments about Russia from users basically trying to get banned, in communities that has nothing to do with this issue.

It's unfortunate, but a lot of valuable older communities are still hosted on lemmy.ml, and I think PieFed users should be encouraged to be constructive and on-topic users there as they should be everywhere else.

An alternative suggestion: Maybe it could be useful to remind people which community they are posting in? Like, "This community is dedicated to renewable energy. Please keep this in mind when contributing to the discussion". Then again, that would be a mess to implement in a good way.