Where is my 2021 recovery rebate credit? I only received the federal tax portion of the refund which was deposited into my bank account by the IRS back in March.

No. it would be included with your refund if you have not received it already

look at the recovery rebate form in Turbotax. you may have to view all worksheets to see it.

most taxpayers would have received it in March 2021.

I see that the $2,800 credit shows up on line 32 "Recovery rebate credit"  and it is included in the calculation for my total refund ($3,725), however the IRS deposited $925 into my bank account.  Why would they not deposit the $2,800 recovery rebate portion? 

IRS denied that because their records show they already sent you that money.