A barter based system could be more susceptible to fraud and scams. Yet would allow for financial transaction outside of CBDC regulation. This could become a necessary step if some individuals and businesses are deplatformed by CBDC. Some businesses can only survive by paying workers under the table.
In practice a barter based system could function similar to ebay with an independent and reliable 3rd party form of escrow. (Blockchain based of course, we aren't complete savages and primitives )
Could a barter system be a worthwhile form of trade past the year 2022. Perhaps the next big leap forward will be a retro move backward into the past.
I believe that it's hypothetically possible that civilizations will revert to barter, but only under apocalyptic circumstances when nothing useless can truly be of value and people use barter simply to survive.