Yes, they exist. If you send a faulty or unauthorized warning, you are threatened with the sanctions of § 97a Abs. 4 UrhG. This is:
Insofar as the warning is unjustified or ineffective, the warned replacement may demand the expenses necessary for the defense of the law, unless it was not clear to the warning person at the time of the warning that the warning was unjustified. Further claims for compensation remain unaffected.
In plain English, this means that in the event of such a warning, you must pay the costs of the opposing side and their legal fees.