I have been living as a white, non-obvious foreigner in Germany for more than 25 years. Nationalism used to be frowned upon until recently, at least the subject was rarely discussed openly, but there are strong, dormant xenophobic tendencies in large parts of the German society, even if noone speaks about it. In the last few years, the nationalist and racist political party AfD has experienced a huge increase in support and is in several municipalities in the eastern parts of Germany the largest political party by number of votes. Expressing racist and xenophobic hatred has definitively become more wide-spread and socially accepted just during the last few years.
I am personally not at all easily scared, but there are for sure areas which I would have avoided, if I had looked obviously 'different', at least some districts in Berlin and many rural areas in the eastern parts of Germany. There are also a few 'nazi villages' in eastern Germany, of which Jamel in Mecklenburg probably is the most famous.
There is of course a large step from having an opinion and to act out violence against foreigners. It is not self-evident that in certain areas of Germany, someone will wait for you behind every rock, looking forward for any chance to beat up a non-white. Racial motivation has been recorded in crime statistics since 1990 and since then, there have been about 200 racially motivated murders. In the recent years, there have been some 1000 to 2000 yearly cases of racially motivated violence across the country. With millions of foreigners living in Germany and many more millions visiting Germany every year, the chances that anything will happen to you are as you can see in general very small. There are however areas with much more violence than in other areas and you might want to avoid them.
Relaxed asked in a comment for statistics and I am aware than you should only believe the statistics you have faked yourself. It is also difficult to find freely available numbers, which are broken down in such a detail that they make any sense. I have for at least a few months, March, July and September 2019 found the number for 'right-wing politically motivated violent crimes' per state. I am fully aware that this number is not exact if we are looking for violence against foreignes in general, but it is the closest I can get. Since the density of the foreign population varies a lot from state to state, I have calculated the number of cases relative to the size of the foreign population per state.
If I set the average index for Germany to 100, we get the following number of cases per state (I have marked the states in former East-Germany with an E):
State Index (Germany=100)
Brandenburg 1182 E
Mecklenburg-West Pomerania 577 E
Saxony 555 E
Thuringia 482 E
Saxony-Anhalt 315 E
Berlin 260 E (partially)
Lower Saxony 54
North Rhine-Westphalia 34
It is worth to notice that the number of cases per state is low and the statistic uncertainty therefore high. In the states of Bremen, Hamburg and Schleswig-Holstein, there were no cases reported in these three months. Alone in these three 'no-cases' states, the absolute number of foreign residents (720000) is higher than in the five states, which are topping the list (660000).