My wife was having a similar problem on her pixel 6. I did some reading and found that their adaptive charging has been modified. If you're not familiar with it, the broad purpose is to slow down overnight charging to be more gentle on the battery. It used to only work when you had an alarm set; in that case it would try to make it hit a hundred percent around the time the alarm went off.
But they recently changed it so that it tries to figure out your normal usage profile, and stretch out charging until you typically start using your phone. My wife has some medical issues that make her sleeping erratic, and it's not unusual for her to be in bed until noon, but sometimes she sleeps okay and is up around 9. She was finding that she'd wake up at 9 and her phone would only be at like 75 percent.
Short version: try turning off adaptive charging.