I saw people mentioning earlier that certain iPad models didn't seem to be charging under Beta 2. I'm having the same issue but it seems sort of wonky so I'd like to share some details of my experience. I use an Anker USB charging hub at my desk and when I first plugged it in I got a pop up saying that the accessory may not be compatible. Seen this before with other chargers and assumed it was just a bug since it's worked fine up until this point. However, while the battery icon changed to charging when I plugged it in, as soon as I dismissed the alert, it changed back to normal as if it weren't charging. Thinking it was a problem with the hub, I tried using an official iPad charger (big brick) as well as an official iPhone charger (small cube brick) and had the same issue. This was concerning as I thought that my iPad was doomed to be dead on this beta but I decided to just leave it plugged in and, although it didn't appear to be charging, when I came back later it was at 100%. So I'm thinking that it's either charging without showing the charging status or possibly only charging when the screen is off (seen this before but haven't had time to test).
Further details: I tested my iPhone, Apple Watch, and AirPods case with the same USB charging hub and they all seem to charge fine so it seems to be an iPad specific issue, at least for me. My issue device is an iPad Mini 4. Hope this helps.