There could be a couple reasons for reasons for this spike. The most plausible hypothesis, I would think, that smokers were at home more due to work-from-home, unemployment, lockdowns etc., and thus would have thus have more freedom to light up compared to workplaces, public events, restaurants etc. where smoking is restricted.
A more outlandish hypothesis is that smokers are buying into theories about smoking and/or nicotine offering some protection against covid-19 and are thus self-medicating.
In any case, my area (San Francisco Bay Area) has an extremely low rate of tobacco usage. Based on what I smell on public streets, I’d estimate the number of cannabis smokers is 2x or 3x the number of tobacco smokers.
There were studies that said smoking prevented COVID-19.
I run some low end rentals. Some of my former renters used their EBT cards to buy high price food items, like the choicest meats and then resell them at pennies on the dollar to buy cigarettes, beer, and drugs. One of them told me, “Everybody does it.” My guess is that there has been a huge increase in EBT or similar welfare. (There’s a way to monetize virtually all of it.) AS a result, there will be a corresponding increase in cigarette, beer and drug sales.
Most likely, these sales are not going to new smokers, but represent an increase in use by current smokers. Even my friends who smoke and have kids report their kids not only don’t smoke, but harass them about their smoking. The worst thing imaginable to happen to any product is for kids to find it unfashionable.