This cover was supposed to be transported by hot-air balloon from Sonthofen, Germany (southernmost town in Germany) to the town of Christkindl in Austria. It was part of the annual and perhaps oldest philatelic charity campaign. Due to strong winds, the balloon could not take off. As can be read on the rectangular Cachet at the bottom left. Also to note is the green Cachet of the Ballon at top left and the both special postmarks applied by Austrian Post.
Stamp:
Christmas (from a set of 3) - Issued: 17-11-2023