MacBook Pro (15-inch, 2017) owner here, I have noticed worse battery life since updating to 12.3 (also 12.3.1) as well. Like, much worse overall. It just seems to drink battery even when not doing much. The performance feels the same, but doing the exact same work I usually do, the battery drains about 30% faster than before on 12.2. I noticed that WindowServer and Universal Control use a lot of CPU when moving the mouse cursor around, even though I have Universal Control disabled. You can see it for yourself in Activity Monitor (change View to All Processes) and then constantly move the mouse cursor around and watch the processes.
SMC reset / NVRAM reset didn't help. I feel like something is using more CPU / GPU than it should, or causing an unnecessary frequency boost when not needed.
I don't think this has anything to do with my battery health, I have a fresh battery (replaced top case) with only around 140 cycles on it, and the battery life is fine again when I boot into 12.2.