Here's a couple sources about it:

Chicago Tribune- Here's an offensive word we should retire right now (2016)

Taking the R-word and adding "lib" to it doesn't make it any less offensive. And what bothers me is that those who combine "liberal" with that word are not insulting their intended targets — they're insulting an entire group of people who have done nothing wrong, all while perpetuating a term that simply needs to go away.

Anchorage Press - Why [word] is Lazy and Offensive (2020)

Combining the R-word with liberal makes it no less offensive.

Cambridge English Dictionary

"An offensive word used by some people on the extreme right of politics to refer to someone who holds left-wing political beliefs"

It's not just us Hexbears who find it offensive. Even if it's used ironically, I think we can all agree that the ironic use of offensive language still has potential to cause harm and should at the very least not be above crticism.

E: I'm pro-federation and I want to soothe things over, and I think the admins of both Blahaj and Hexbear are committed to that, but it seems like this mod is intentionally trying to burn bridges. This all happened underneath a post where they publicly posted a private conversation with one of our mods for the purpose of mockery. I've been trying to get people to tone it down on our side, but none of our people are going to listen to calls for civility in the face of ableism. We support our neurodivergent comrades.