I'm confused about what to do in my current situation.

My girlfriend broke up with me because I was being too clingy and needy, and I was acting out of fear, I really didn’t know what to do back then, a week later I found her with her old Ex, they’re together now, but based on all of my info, they’re not as close as we were during our relationship.
I decided to do No Contact, and tried hanging out with my friends, focus on my happiness, and improve myself in general. about 30 days have passed, then I started contacting her again, and I followed this Article to text her : https://exbackpermanently.com/use-texts-to-get-your-ex-back/.
It was going pretty well, we had friendly, fun conversations, at first she even started replying pretty quickly and seemed excited about it. Then on her birthday, I got her some chocolate for a present, something not too expensive yet pleasuring, she was really happy and even hugged me and I could feel her excitement.
But then.. On my 10th day after starting contact, without any reason at all, she started ignoring me..?
All I said was “Good morning” and then she left me on read, it seems pretty odd to me until now, so I’m pretty confused.
I was thinking of the possibility that she’s just confused about her feelings, or maybe she’s afraid of developing feelings for me again..? But I really don’t know what to do.
We haven’t even talked about anything really serious or anything related to our break-up or old relationship. We’ve only been acting as friends, and suddenly this happens..
It’s been 3 days since that happened, and today I sent another message asking “Is there something wrong?” and well, no reply yet.
Please help me out with my situation, I’m really clueless about what to do.
Thank you.