Sleeping baby no more!

Recently my 8 month old has decided she wants to sleep during the day and not at night anymore and I’m losing my mind as I also have a 3 year old. Any ideas what this could be or why she’s doing this? Her new normal sleep schedule looks something like this; nap at 11 or noon for 2-3 hours, nap at 4 or 5 nap until 7/7:30 go to bed at 9 wake up around midnight or 1 am stay up until 4 or 5 am and then sleep until 10

If anyone has any types of ideas I’d very much appreciate them, I need her to sleep at night again!! 😩