So I imagine there are multiple reasons for the trend, but it’s still interesting.
I'd be curious to see if there's a difference in negative reviews when divided by regions with different COVID infection rates.
We need more data.
If you can’t smell the candle it’s probably you.
Lack of smell is a characteristic symptom of the coronavirus, including in otherwise a symptomatic people. The proportion of reviews (2->6%) pretty clearly tracks the increased caseload of the virus in the United States.
While you are technically correct, this phenomenon is almost certainly due to the virus.
I also find it rather shocking how nonchalant people who likely consider themselves educated and scientific, just jump to rather dangerous conclusions; dangerous in that it can contribute to hysterics that have been driving this pandemic response and has us in a catch 22 type situation.
The big question is what are they buying. If these reviews are coming from people buying the same brand/scent as before, then Covid related scent loss is the most plausible explanation (although I wonder why some one in such a situation would bother to leave a review....). But if these shoppers are buying new scents for fun or availability reasons, it’s hard to separate those who are losing their smell due to Covid from those who are just dissatisfied with a candle they purchased scent unsmelled.
Fake Jo Malone candles have been reported as having catastrophic glass failure  or containing a number of bad news chemicals.
I could smell the very first candle I picked up. After that the cacophony of smells was apparently too much for me and I couldn't smell anything at all until after I left the store.
So I guess it could be that they all have coronavirus, but it seems just as likely that they've all been cooped up inside their houses with probably overly filthy air and their noses just can't take it anymore.
Sometimes I have to use the fairly fancy department store in Copenhagen (Magasin). I often walk all the way round, so I can enter in… handbags or something, I don't know, I just know it doesn't smell. The more convenient entrance is to the perfume section, which makes me gag.
I have no problem with person-quantity perfume. I found the signs in California about a "scent-free workplace" a bit strange. Some shops just have enough perfume to knock out a horse.
(Many years ago, I had a job working in a chocolate factory for the summer. I couldn't eat chocolate for the whole summer, after the 8 hour exposure every day, but it wasn't unpleasant. I bet there are food industry jobs where the smell really is unpleasant.)
I routinely get sore eyes when I visit my sister-in-law, who loves scented candles. It's that or her cats, although I've never noticed a reaction to animals elsewhere.
At this point, birds and cats are about the only animals that I cannot have in my house.
Scent allergies are also common to develop as you age. My mother used to love scented things, but hasn't been able to have them for going on 20 years.
I wouldn't rule either out, to be honest.
It is very interesting why it works. The source of the antigen is a bacterial infection they lick onto their fur. Eliminate the infection -- really, replace it with a different one -- and no more dander problem.
For my part, I have a positive reaction to Lush shops. Almost too positive a reaction: I want to eat all that I smell, and I have to remind myself that those are soaps, they are not edible.
There must be people that get full blown anaphylactic shock.
But people get really offended when you mention anything negative about the invasiveness of their perfume or makeup!
Candles have a social purpose. When no one is coming over, there is less need to make the house smell nice quickly. ;)
Scented candles are sold in malls, which have not been visited much this year.
Scented candles are given as gifts (to aunts, etc.), and many birthdays have been forgone this year.
Candle-making is a popular hobby this year.
Edit: weird downvotes. It shouldn’t need to be said that these ideas are presented for discussion. They’re not political statements.