edit: paper shared below!
https://jech.bmj.com/content/jech/early/2020/01/03/jech-2019...
If this result stands up, it'd be very interesting to drill in and figure out what's really happening. Quite challenging, though--apparently long study hasn't even settled the question of how minimum wage affects the job market.
In this case, one could imagine all sorts of confounders. For example, maybe communities that have higher minimum wages simply have them because they're wealthier as a whole, which could in turn lead to lower suicide rates. Or perhaps a higher minimum wage leads to the most marginal workers losing their jobs, and it turns out that they're happier for it somehow.
If you a see a piece of research that seems to contradict some elementary principle of economics, it's possible that the researchers somehow forgot all about it or never learned it and that the paper somehow passed out of peer review without anyone pointing out its glaring deficiencies, but it's more likely that that an elementary understanding of economics is insufficient to explain real world phenomena.
You can see a parallel to this in the climate science debate, where people object to scientific assertions on the grounds that the sun is very much hotter than burning fossil fuels or 'climate is always changing' and human activity is too nebulous to possibly have an impact. Often deliberately simplistic arguments are used to mislead the slightly-educated and discourage them from becoming better informed.
Seattle--a world-class tech nexus point--raising its minimum wage affected a relatively small percent of businesses compared to a "normal" city, as businesses in Seattle would have long since needed to offer higher wages in order to keep employees.
I'd be much more interested in seeing the effects of a $15 wage in Nowheresville, USA than in Seattle.
"Normal" towns' leaders would recognize it as virtue-signaling rather than transformative change, because it would've affected proportionally few people.