There are many problems with this post and this study:
This study did not conclude that there are no health benefits from taking multivitamins, that's a false equivalence made by the poster.
This study has no parameters for the quality or types of vitamins taken other than "multivitamin"
This study exclusively reports the correlation between mortality and multivitamins, which is an inconsequential and useless statistic without any parameters.
This study does not take into account any variables apart from a lack of long-term health disorders among multivitamin takers.
This is relevant as many people take vitamins specifically to rectify long-term health disorders.
Then again, seeing as how their only metric was mortality and not efficacy on health, that wouldn't have mattered in this study.
Objectively, a large percentage of the multivitamin market are older people, who are more likely to die.
This could be one of the explanations for the 4% higher mortality rate in multivitamin takers. I'm sure there are others, since no variables are parameters were taken into account or structured into the study. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2820369
This "study" is the sum function on an Excel sheet that counted the number of deaths connected to the number of people who reported taking multivitamins, which is a useless number without controlled parameters or variables taken into account.