Why does it always say my federal refund is still being processed ?

Because the IRS is still processing it.  They are way behind.  

Turbo Tax only gives you an estimated date. The IRS usually pays most refunds within 21 days. But these are not normal times. This year is taking the IRS longer to send the refunds. There are millions more people filing returns to get the Stimulus payment.

See this news article on Refunds being delayed
https://www.msn.com/en-us/money/personalfinance/where-is-my-damn-irs-tax-refund-new-answers-emerge-as-delays-frustrate-millions/ar-BB1g54Ks?ocid=BingNewsSearch

Only the IRS can tell you. If your return was Accepted then check IRS Where's my refund
https://www.irs.gov/refunds/

When will you get your refund?
https://ttlc.intuit.com/community/refund-status/help/when-will-i-get-my-irs-tax-refund/01/25589

IRS - Questions about Refunds
https://www.irs.gov/refunds/tax-season-refund-frequently-asked-questions

At the sign post up ahead, the Twilight Zone for tax refunds.