I think these stats need more explanation.
I did some searching and found that, in addition to different terms for mass shootings, there are some that do/don't make the list. (UNCC shooting didn't make Mother Jones list, but did make it onto the Wikipedia list)
This article from Mother Jones shows that there were only 4 mass shooting incidents in 2019.
Wikipedia shows that there were a lot more. (probably 150, I didn't count them). From that site:
When you look at the Wikipedia list, it appears that a good portion of those shootings could be gang related.
Are proposed gun regulations going to do anything to reduce those deaths?