So it is in the fine print on paxlovid, a common side effect cited is an "altered sense of taste" (dysgeusia, for those in fancy pants.) It slips past the liver warnings and contraindicated drugs.
On the first day I was too miserable to care about it, by day 4, that taste is something I think about... What is it really? #paxlovidmouth
While brushing my teeth, the taste was intensified and a light went off... Probably thanks to the sodium lauryl sulfate.
I ran downstairs and dug it out from deep within the bar and tried a little and that's it! The bitterness in here with just a little metal (not copper, more zinc-y, maybe?). The taste may have been more intense due to the sodium lauryl sulfate and whatever is going on with the antivirals.
So we've evolved to have a lot of different senses for bitter, because bitter tend to be the things that kill us. Not as many varieties for the stuff like sweet. So it makes sense: if something goes off-kilter with taste, bitter will be in involved.
It seems ritonavir is the actor, just based on reports for its other uses over the last 20 years...even a paper published in 1999.
Electrojcr