The COVID 19 RT-PCR specificity results were shown in this FDA document (Table 9 on page 45): https://www.fda.gov/media/134922/download

I had an argument on another site with someone making a similar claim about why I think the flu results started turning up mostly negative and why flu death attributions are basically non-existent this year, but I think it just muddies the point. The COVID PCR tests that have been used over the past 12+ months are accurate and do not conflate COVID with Influenza.