Hi again,
google webmaster console checked the pages and get a double meta description on the event pages. This leads to bad rankings.
Examples:
https://www.szenenight.de/netzwerk/partykalender/5640-roofnight.html
https://www.szenenight.de/netzwerk/partykalender/5639-roofnight.html
Pretty the same event but for an other day. So the solution is to add date and name infront of the event description to the meta description.