From the article: *Large SUVs were particularly affected. According to the police, notes were attached to the cars indicating that they were harmful to the climate. The tyres were not punctured, but merely deflated. The cars were parked in the area between the S-Bahn line and Elbchaussee around Kanzleistraße. *
Personally, I like this protest way more than glueing themselves to the streets, causing traffic jams where cars burn gasoline for hours and ambulances / firefighters / police gets stuck, putting innocent life in danger.
The article is in German. Warning: this link leads to google translate.
They’re not leaking the air out while the car is driven. Modern European cars all have pressure sensors and will warn the driver when there isn’t enough air in the tires to drive safely. Saves you from walking around the vehicle to see if everything is tied and pumped up properly.