We received a message from the admins saying that we broke "MCC Rule 3".

Rule 3: Respect Your Neighbors

While we allow meta discussions about Reddit, including other subreddits, your community should not be used to direct, coordinate, or encourage interference in other communities and/or to target redditors for harassment. As a moderator, you cannot interfere with or disrupt Reddit communities, nor can you facilitate, encourage, coordinate, or enable members of your community to do this.

Interference includes:

• Mentioning other communities, and/or content or users in those communities, with the effect of inciting targeted harassment or abuse.
• Enabling or encouraging users to violate our Content Policy anywhere on the Reddit platform.
• Enabling or encouraging users in your community to post or repost content in other communities that is expressly against their rules.
• Showboating about being banned or actioned in other communities, with the intent to incite a negative reaction.

New Rules as of Today:

1. No more mentioning r|Europe or r|DE. It's the one big sub that isn't allowed to be named anymore. Moreover, any comment with a subreddit in it will AUTOMATICALLY be blocked. This is something Reddit forced upon us just now. We can't undo it.
2. No more mentioning mods of other subs. We do not allow any mentions of mod's nationalities (eg. brazilian), religion or location. <– I was already removing these comments, but now it's official.
3. No more "I got banned from r|Europe". We do NOT wanna risk being seen as "bad neighbours", even if it's not rule breaking.