Is it possible that there are false negative test for covid because the disease is mutating?

We know about false positives but there also seems to be false negatives as well and it has me wondering if the test won’t work on a mutated version of the virus. I also am wondering if it has mutated because I read that some people don’t get it real bad in their lungs. Some show damage to intestines and heart and other organs and little to no damage in the lungs. It’s a low percentage of asymptomatic people. I was listening to a doctor on the news that said the people who are hospitalized for COVID who have bad diarrhea seems to have a higher death rate than the rest.
So it had me wondering if perhaps there are more than one version of the disease and if that can effect the accuracy of the tests.