There is a genuine gap, in three phases
With the app off you are on your personal policy. Once it is on and you are waiting for a request, the platform typically provides only limited liability and nothing for your own vehicle. From accepting a job to completing it, cover is usually broader. The waiting period in the middle is where most drivers are thinnest and least aware of it.
Delivery is treated the same way
Carrying food, parcels or groceries for payment is commercial use on a personal form, including in your own car for a few hours a week. The exclusion does not care whether it is a full-time job or occasional extra income.
A rideshare endorsement is the straightforward fix
Most carriers now offer one, it costs modestly, and it closes the waiting-period gap and extends your own collision cover to it. Driving without one is a decision rather than an oversight once you know.