If you decide to continue with Turbotax...the upgrade is usually required by some situation in your tax data that requires certain tax forms that are not a part of the "Free" version. The "Free" version of TTX is only for very...very...very simple tax situations.....Very simple. There is apparently some credit, or deduction, or other situation that requires Deluxe (or higher).
Some folks with pretty-much only a W-2 and started out OK in Free, might have sold a few Mutual fund shares and had (say) $10 of gain...but that mutual fund sale requires Premier...more expensive than Deluxe.
The only credit I can think of that can be bypassed to avoid an upgrade is the "Retirement Savings Contribution Credit" (RSCC). Soem people with simple tax returns, may have some contributions to a 401k on their W-2, that gets them an RSCC credit that is far less than the cost of the upgrade (plus $50 state too). They can go thru the RSCC interview and indicate they were a student in 2019, then the RSCC (supposedly) goes away.
But there are myriad other reasons for a required upgrade to Deluxe...and unless some display page indicated exactly why...we have no way to guess what's in you tax file that prompted it.