Our legacy freenode channels are now set up to minimize the risk of freenode hijacking them again while still directing users away from it.
Channels are +m but the matterbridge bot is there in output-only mode with +v to show people the channels are as active as ever elsewhere.
Conversation
The topic and entry message tell people that we moved to new Matrix rooms without explicitly stating that we moved away from freenode or mentioning libera.chat which we bridge bidirectionally.
It's ridiculous needing to walk on eggshells but this should work well.