DNA companies themselves admit that their testing isn’t 100% accurate. One of my tests said I was 93% Irish while another test said I was only 80% Irish. The less than 1% totals are particularly inaccurate. Those are basically statistical noise that may not even be real. There are some white Americans with distant African ancestry, although it’s a lot less common than liberals pretend it is. And why shouldn’t a person with 1/32 or 1/64 black ancestry be considered white anyway? (Unless you’re some kind of believer in 1930s Alabama hypodescent laws.)
The ethnicity portion is an evolving science. There are tools on gedmatch.com that offer a deeper analysis, especially for non European ethnicities.
The real gold, at least to me, is the matching to other users. Many people have been reunited with family, especially adoptees. *raising hand*