Last year the problem was that the IRS fax machines were running out of paper and ink, and the companies that maintain them couldn't get in to service them.  This year, the Journal of Accountancy reported about news from the Treasury Inspector General for Tax Administration:

Inadequate equipment also impeded timely processing, TIGTA found. For example, the IRS for the most part is unable to directly import a faxed document from a taxpayer into its computer systems but must print it out and scan it (it also generally scans all paper correspondence received). IRS managers in response to TIGTA's recommendation asked the Service's information technology office last October to implement an electronic connection for faxes, but as of early January this year, the technology had not been implemented, TIGTA reported.

https://www.journalofaccountancy.com/news/2022/mar/tigta-irs-inefficiencies-worsened-backlog.html

Even my most technologically-backwards clients know how to scan a document, or take a picture of it, and send it to me as an email attachment.  IRS is our national disaster area -- they are doing things the way they were done 30 years ago, except they don't have the resources to do much of the necessary work.