I just discovered that swiping left on a locked iPhone no longer opens the Camera app. It's now a tiny icon that you press at the bottom right, opposite the flashlight icon. That frustrated the heck out of me until I noticed the icon. They should make it a bit larger.
The little camera icon way of opening the camera has been there for at least 4-5 years, along side the swipe from left to right method. The latter is less discoverable which may explain the icon. I just tried the swipe method on my 13 Pro Max on the 15.1 beta and, like the others who have reported, it works just fine.