I found:

"However, in Information Letter 2020-0024 the IRS cautions that the qualified transportation plan regulations do not authorize cash refunds of qualified transportation fringe benefits that are provided through a compensation reduction agreement.

IRS Information Letter is available at: https://www.irs.gov/pub/irs-wd/20-0024.pdf

"

In response to a letter asking about that scenario because, due to covid-19, an employee is no longer using that benefit that is prefunded by salary reduction.

https://www.wagnerlawgroup.com/resources/health-welfare/irs-confirms-options-for-unused-qualified-tr...

Also: https://www.irs.gov/pub/irs-wd/20-0031.pdf

Also, search this for "QTF" or "salary reduction": https://www.irs.gov/pub/irs-pdf/p5137.pdf

I wasn't aware of it; it acts like an FSA for commuting.