Hi Kazi,
The pellets are good nutrition, but not quite as good as the formula. But do not force the bird to eat formula. Just keep offering it. Some will get independent like that for a few days and then want to be hand fed again, because they really aren’t getting everything they need from self feeding at that age. Be sure and offer all of the other foods I mentioned, and not just pellets. As I said, weaning is gradual and birds often go back and forth during this process, as far as reverting and then making progress again.
Thank you for asking Lafeber,
Brenda