I can't speak to covid because I've never had it, but "take it more serious" can be applied to large swaths of valid medical issues in which doctors brush off as "it's just in your head". In my own case, they quickly jump to the conclusion of stress/anxiety/hysteria without ever asking about my history or my life and without doing any kind of lab work or imaging diagnostics to rule out the medical issues. That is dangerous and thousands of people actually do go untreated for chronic illnesses like MS, Parkinson's, SLE, etc. every year because their providers do not take complaints as serious medical concerns. IMO PCPs are not in a position to adequately diagnose mental issues (especially in a 15 min appointment); that's why we have psychologists. Yet they throw around diagnosis of mental illness like they throw around opiates.

It's an issue of perception and condescending attitudes by medical professionals that is the real problem. If I were a medical professional, I would at the very least acknowledge the problems as genuine physical symptoms and do my best to re-assure the patient that it's being researched by the scientific community so a treatment might be possible in the future.