The M and S marks are not genuine winter tyres unless the three peaks (winter symbol) is also marked on the sidewall.
Three peaks is only a recommendation
The new law also spells out what a "winter tire" is. Specifically, it is an M+S-Reifen, a mud-and-snow tire that has an official M+S (Matsch und Schnee) marking on it. (M+S tires do not have to be "winter" tires. All-year or all-weather M+S tires also qualify.) The German automobile club ADAC recommends going a step further and getting tires with the "three-peak-mountain" seal, an indication of snow tires that meet the highest standards.
german-way.com/travel-and-tourism/driving-in-europe/driving/snow-tires-winter-driving