According to a comment by the State Data Protection Commissioner of Baden-Württemberg on Twitter there have been around 1500 warning letters in Germany since February 2019 due to alleged violations of the GDPR:
@Martin_Raetze Aha.
There have been over 1,500 warning letters since February 2019. Don’t you know that?
In BaWü, doctors and their websites were particularly affected.
That is far more than previously assumed. In Baden-Württemberg, doctors and websites were apparently most affected.
The legal admissibility of warnings for alleged violations of the GDPR remains in place unsettled. In Germany, therefore Efforts underway, to restrict abusive warnings by law.