Hello.
I installed the last 18 update this week, since I installed this my iPad Pro 11-inch (M4) has been very, very hot.
latest ios 18 beta update has my ipad running very hot
The forum is for questions about app development, not about products use.
You'd better ask on Apple Support Communities: https://discussions.apple.com/welcome
This is about the iOS 18 beta, so I'd say this is the right place to mention this.
However, OP, this is generally expected. A beta version contains diagnostic processes that aren't present in a release version, so you should expect your iPad to be doing more than usual.