German-Americans were not interned en mass like Japanese Americans who lived in the western US.

More detail for both groups is needed. My research was on Japanese American internment so I'll start there. Japanese Americans at this time can be divided into a few categories

Issei- Japanese immigrants (aliens) to the US. Legally barred from naturalization because of their race

Nisei - Children born of Issei, American citizens by birth because of the 14th amendment.

Sansei- "3rd generation" Japanese, born of Nisei parents.

Fully 2/3 of the Japanese interned were born American citizens, out of 120,000 people total. Contrary to popular belief, Japanese-Americans living outside of the western US were not interned indiscriminately, but since most of them did live in the western US this meant very little.

Racism towards Asians in the western US had been going on since the 19th century, first against Chinese, and then to Japanese as more Japanese immigrants arrived in the early 20th century. Laws against "alien" land ownership were passed in CA and other western states, and later overturned by the SCOTUS. Japanese family's got around those laws by putting land in their babies' names, but those Nisei still faced legal and cultural segregation before the war.

Anti-Japanese (and more limited Anti-Asian) racism exploded with Pearl Harbor, culminating in the internment of 125,000 or so Japanese Americans. They had to sell their property at firesale prices, with no method of challenging their imprisonment. Korematsu v United States upheld this internment, despite Fred Korematsu being an American with 0 connection to Japan aside from his race.

Asian people in general also had to deal with whites thinking they were Japanese. Koreans, in particular, fought in court to be recognized not as part of Japan, since Korea had been conquered by Japan earlier in the century. Chinese people would also sometimes carry flags or mark themselves in ways to try and ward off attacks, as can be seen in this photo and others linked in the thread.

The situation for German (and Italian) Americans by and large were left alone, unless they were German aliens or connected directly to the Nazis. Direct sympathizers, such as members of the German American Bund (Nazi lovers) faced more legal pressure. Fritz Julius Kuhn for example was a naturalized citizen, who was deported and had his citizenship canceled in 1943 for leading the Bund.

Cultural discrimination towards Germans and the German language was common as well. As German at the time was the most common language after English, it was easy to target German-speaking immigrants for discrimination. My grandfather's parents told him stories of being accosted in public for speaking German, and social pressure definitely contributed to the decline of German-speaking churches, newspapers, and businesses after WW1. I don't know many specifics about the same process in WW2,

A great resource to learn more about all of this is the Densho Encyclopedia. It contains good summaries of everything I've said, and a primary source database I used for my undergraduate work. https://encyclopedia.densho.org/

source for German language discrimination, WW1 and afterward https://blogs.illinois.edu/view/25/116243

Source for US Govt policy towards Germans/ Italians vs Japanese. Personal Justice Denied: Chapter 12 https://www.archives.gov/research/japanese-americans/justice-denied

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Photos

https://rarehistoricalphotos.com/chinese-americans-during-ww2-1941/