Loud hammer noise when toilet is done flushing

I'm pretty sure from my research I need a water hammer arrestor. Basically the toilet makes a loud bang noise after it's done flushing. It's been that way for a bit. I am attaching a video of the toilet flushing. Is this something I need to worry about? Thank you.

https://reddit.com/link/183zvwv/video/k3vq1miool2c1/player