Upgrading Camera

I currently shoot sports on a D3300. I’ve been saving up money from my shoots and i’m up to an amount where i’m comfortable with purchasing a new camera. I have a tamron 70-200 f/2.8 G2 lens so I would need an adapter to switch to mirrorless, but mirrorless is the goal. I’m looking at switching to a Z50ii and was wondering how much of an improvement that would be. My biggest issues with my current setup is the low light performance, and very slow, and not crisp focus. I also plan to try out video so I’d love if the camera was video capable. Thank you for any help!