iPhone 11 Pro Max, currently on iOS 26.1 No issues.
During the first beta of iOS 26, I mean the one I first installed, I had a big battery hit at the very beginning. However, after a day or two everything returned to the same normal I had on iOS 18. So, I attribute that to whatever background processes needed to shake out.
I'm a fan of Liquid Glass. For the first time my stock iPhone is starting to look like the jailbroken versions I had from 2011 to 2020.