You clearly don't know what you are talking about. PCR tests for nucleic acids (e.g., DNA, RNA). An immune response results in antibodies (proteins), which can be detected using antigen tests. Yes, the PCR test is too sensitive. At high cycle thresholds, it'll pick up cleared viral nucleic acids.
This site has really gone to shit with its understanding of science. I've seen scientific misunderstanding all over the notables the last few days.