School being back on isn't a satisfactory answer to why there's a such a large increase. It went from 124 in 2019 to 349 in 2023, nearly 3x as many shootings.

I don't know the answer but I would guess it's either Covid's social isolation effects on people, more societal stress with high inflation, an impending recession, and unknown job future for many, or Tiktok/social media becoming a bigger part of our lives.