This claim of responsibility was just found at Indymedia:

Last night we sabotaged eight construction machines in the area which is to be prepared for the opencast mining.

At five excavators, two bulldozers, a road roller, and another, expensive-looking thing, all hydraulic hoses and electrical cables that were reached, were cut. The tanks and oil filters were filled with sand, all the windows smashed, and other mechanical components sabotaged. Despite all the security measures taken by RWE, this action was carried out with no problem.

This action is directed against the opencast mining operator RWE and its collaborators, who destroy the livelihoods on the planet just for profit.

While the vast majority of people in Germany sits silently in front of the screens of their TVs, distracted from the daily destruction by smart entertainers and prophets of the permanent growth, die in other parts of the world already hundreds of thousands of the effects of climate change, partly caused by RWE.

While most people should be aware that it can not go on this way, it unfortunately is until now only a small minority who is willing also to take action against the destruction and who thereby are putting their own health and freedom at risk.

Actually, three of these people are sitting in prisons in Cologne and Aachen, for their attempts to prevent the destruction of the Hambach Forest by RWE.

In the course of their captures, all three were abused either by the police or the security service of RWE, one person’s nose was even broken and several teeth were knocked out.

We therefore wish to show solidarity by means of our action especially with the actual detainees and make clear that we will not be intimidated in any way. Because it’s about all!

Hoping to motivate more people to such actions,

The Chaos Engineering Crew