Weird sleep question

So my 7 month old has been sleeping through the night since first week of September. She usually goes to bed between 6:30-7 and wakes up at 6:30ish.

Recently she seems exhausted by 8am and I usually try to push her wake window to 2.5-3 hours but she just can’t make it.

Well the past few days I’ve been waking myself up at 5:15ish and I’ve noticed when I turn her monitor on her eyes are open! She seems awake. But she isn’t crying and she just stays laying there.

So what should I do?? I mean every day I hope “maybe she will fall back asleep” and it kind of seems like she does dose back off but why is she waking so early and then just laying there??