I was supposed to be receiving over $3800 and only got $1600 after it had already been approved.

I think you mean Accepted (for processing).  Approved is a later step, and the IRS can still adjust your return.

Wait for a letter from the IRS; they do not notify TT.   But the government validates all Recovery Rebate Credits against its records of stimulus payment that were already sent out.  Some of those were sent as debit cards. Could you have received one, but threw it out as junk mail? 

We received 2 separate stimulus checks via direct deposit. This is reflected on line 30 as $2200. I am seeing a lot of people posting on social media that this is somehow a widespread error with Turbo Tax and people are having delays and changes to the refunds. I looked over my tax documents and everything looks correct, but the irs said the claim had errors with SS numbers of dependents