Misleading titles. It's certainly not "illegal", as long as you have consent. Besides, there is no law specific to "Google" ... What would be the point of that? The law is about forwarding the visitors IP address to 3rd parties, when it is "not necessary for the website to function", unless the visitor accepts. Besides, there has only been one single ruling on this in one country.
Should you avoid Google fonts if you are in Germany?
Probably, just to be safe. Here is the current fix:
Below is the original post discussing the issue.
I will be changing your post title, because it's misleading.