What could this be? Does anyone have an idea?

I moved out of a flat in June and haven’t really spoken to my ex-flatmate since then.
Yesterday, I WhatsApped my ex-flatmate to ask how she is doing. Her WhatsApp profile changed from initially blank to having the old picture and status that she had prior to losing her phone once in late July (we messaged a couple of times in August), implying that she very likely noticed my message and added me back to her contact list.
It has been over a day and my message remains Delivered (double green ticks). She has been online on-and-off, but has not responded to me.
What does this mean? Does it mean she does not want to speak to me again?

I would assume she doesn't want to speak to you, or just doesn't know what to say.

You are right. She asked me not to contact her again based on the exact reason I suspected. It is devastating that she has not really forgiven it despite what she claimed before. I feel extremely dumb for having made all the apologies and attempts to redress her “grievances” when the other side simply wants to make me out to be a villain because of whatever reason(s) only known by themselves.

I would just let it be, don't dig up old wounds.

I want to cry.

Then cry, but if you guys have history that's better to leave than dig up, try to move on as best you can.