After you file

There may not be a clear answer to my question and that is ok.  My bank account information has not changed in the last 4 years.  All of my tax returns in the last 4 years has been deposited into the same bank account.  My status from the IRS before this Friday, indicated that the stimulus would be sent to my bank account, displaying the last 4 digits of my account.  ON FRIDAY, the message switched to "it will be mailed on 3/26/21".  My question is why the switch when they had the correct information all along.  I have not had ANY issues in the last 4 years with receiving my refund and/or stimulus to my account.  Before Friday, everything was set up for it to be direct deposited.  NOW - it says it will be mailed.  AND - that's not just my story - there are others who had the same thing happen to them.  So, I was just trying to see if there was a standard reason why in mid-process they would change our method of receiving the stimulus from direct deposit to mail, if they have the correct bank account information and for years has been sending it to the correct account.  Like I said, there may not be a clear answer to my question, and that's fine.  I was just curious and a little concern that something did not transfer correctly with my information.