Why is my TurboTax saying that my return was accepted, but the IRS is saying that it's been received but not accepted?

When TurboTax says your return was "accepted", that's just an efile term that means your efiled return was accepted by the IRS to begin processing; i.e., the IRS found it to be in proper format such that they could start processing it.    Once an efiled return is accepted, TurboTax will continue to show the status as accepted.   The IRS does not use the term "accepted" in it's WMR tool.    That's different than the word "approved."    The IRS usually uses these stages:  "Return received" then "Return approved" then "Refund sent."

TurboTax provides an estimated refund date based on a common 21-day average.  But some returns take longer to process or need more examination by the IRS, especially this time of year if a return has certain credits such as EITC or ACTC.

You should go by whatever is displayed at the IRS "Where's My Return" tool.

https://www.irs.gov/wheres-my-refund