Your 1099-K reports payments from third-party transactions (in this case, from riders to drivers). Payments are calculated from fares, tolls, sales tax, city fees, airport fees, split fare fees, and booking fees.
The booking fee is a separate flat fee added to every trip that helps support safety initiatives for riders and drivers as well as other operational costs.
Note: not all states have a Booking Fee. If you drive in California, riders are instead charged a Marketplace Fee directly.
To understand if the booking fee is deductible in your situation, it is recommended you contact an independent tax professional.