Yeah ok that's exactly what it looks like, automatically sending out notifications with local holidays as the title: https://images.app.goo.gl/1hQR3gpy9wcCdsKT8

I do wonder where they pull them from tough. I searched for the exact wording of the holiday and figured it would pop up in a Wikipedia "List of Holidays in Germany" or something, but it doesn't seem to be in any public list.