Waking up earlier and earlier 😩

My 8 month old has been taking 2 naps a day for a while now and they seem to be about an hour and a half long. Her bedtime routine starts about 630 and she's asleep by 730 at the latest. She used to wake up at 7am. It's been getting earlier and earlier ever day though and now we're waking at 5! My older 2 did not do this so I'm lost as to what to do. She is still obviously tired at 5 but we can't get her to go back to sleep. Going in at 5 to put her back doesn't help, earlier or later bedtime doesn't help, and we already have blackout curtains. Is anyone else dealing with this or have any advice?