You are still supposed to wake up at 100%. But it gets you to about 80% while you sleep, and then predicts when you are going to wake up and tries to get you to 100% right before you wake up. Supposedly this is better for your battery, but the goal is still to be at 100% when you wake up.
Is your sleep schedule unpredictable lately? Something sounds wrong here (sounds like you still have plenty of battery for the day which is good, so not a huge deal.)
Apple’s website says, “The algorithm aims to ensure that your iPhone is still fully charged when unplugged.”
Here’s my battery chart from last night. Woke up at 100% with the setting on