IRS keep sending similar LTR12C

I filed 2021 tax return on April with Turbotax E-file. I owed tax so I paid the owed amount with my e-file.
On Oct. 20th, IRS sent me LTR12C, asking W2, Schedule 1, A ,D. I was not sure why they were asking them since these were in my e-file. However, I faxed those  and the supporting forms with a coverage in their requested format. 
Today, Nov. 15th, IRS sent another LTR12C. Now, they are asking Schedule 1,D and 3. I’ll sent those with supporting documents but I have no idea why they are asking Schedule 1, D again which was both in my original e-file and my response in Oct. I have reviewed sch. 1, D, 3 and found no error. And all supporting forms like Form 8936, 5695, 8949 and even 1099G were in the original e-file and my response in Oct.

Can anybody advise me what this repeating LTR12C really implies ? Does IRS really review it throughly and found error so sending me LTR12C ? I have reviewed my forms multiple times but there is absolutely no error so have no idea what to correct if they are going to ask these again.  Moreover, I paid what I owed, not receiving a refund. Is IRS trying to charge me more ?