Why do my cash contribution carry-forwards from 2016 and 2017 now show as non-cash contributions carry-forwards?

Not sure why that is the case.  Cash contributions that were not deductible in a given tax year can be carried forward for up to five years.  Moreover, they should maintain their original character, meaning that your cash non-deductible contributions from a prior tax year should have remained as cash contributions in subsequent years.

Cash contributions you carry over are subject to the same percentage limits in the year to which they are carried. 

Given that your cash carried forward charitable amounts are now showing as non-cash contributions, it may be prudent to review your 2020 return and determine whether the amounts at issue reflect their cash status.  Going forward, you can re-enter the cash carried forward amounts.  In this regard, if you are using TurboTax online, after logging into your account, go to the Deductions & Credits section.  Scroll down the page to Charitable Donations, click on the down arrow to open the selection menu and select Charitable Donations Carryover from 2020.  As you move through the application you will get to the page that will ask you about prior year cash donation carryovers (you will first be asked about non-cash carryovers).  Enter your information in the boxes provided.  

In TurboTax desktop, you can enter the term "donations" in the search bar.  Click on the jump to link and at the page Donations to Charity, select "no."  The next page will be your 2021 Deductions & Credits.  Scroll down the page to Charitable Donations and select Charitable Donations Carryover from 2020.  The pages that follow are essentially identical to the pages in the online version of TurboTax.  Enter your information accordingly.