And the "wave" was a handful of unrelated fires that happened near churches (not even in churches for most of them) over a few years and were mounted as a "wave of arson" by extreme-right websites during the height of Syrian refugees influx.

The original website that had a map of these events (that you had to look up yourself to see they amounted to nothing) isn't even online anymore as far as I can see, now this false fact is just a urban legend with a life of its own.