I thought it was an iPadOS beta bug
This morning, I updated my iPad to iPadOS 26 beta 3. Ever since I installed the beta, my Apple Pencil hasn't been working. I figured it was a beta bug and hoped beta 3 would fix it. No luck.
So I did some digging and found out Bluetooth wasn't detecting the Pencil. It turns out that you have to re-pair it after installing the beta. The fix was simple: plug a USB-C cable between the iPad and the Pencil. It paired right away, and now it's working again.