Ex gf (19F) ghosts me (20M) after a week of talking

Hello everyone, I (20M) about a week ago reached out to my ex gf (19F). we’ve been on and off for about 3 years but now she’s graduated school and I’ve gotten into a better place, I reached out to her to just talk and catch up after some time apart, and she was surprisingly into it.

We talked non stop everyday for a week, she really missed me, telling me she was just about to reach out and was happy I did it, and we threw some flirts back and forth and whatnot before suddenly she ghosts me.

It’s been about 3 days, I texted her on the first day to talk, nothing. So I waited until the 3rd day to send a light meme on Instagram and still nothing.

Her following number goes up still so I know she’s been active on her account, and it’s not like her to be away from her phone so long.

I’m simply just curious what’s going on? Why would she possibly ghost me after a week of seemingly perfect conversation and rekindling?