After you file

I filed my return on February the 1st it was accepted on February the 12th I also had to claim the recovery rebate credit and I still have not received my return the where’s my refund app doesn’t even show the bar anymore every time I check it.. it says my refund is still processing and a refund date will be provided when available  and now they say they h ad to make changes and my refund is like $1000 less then what I filled out. Also, I would be getting a letter saying the issue for the changes. Why?

There is nothing different this year with me and has not been in the last several years