Probably because your Selling account is unused for more than a year and may need updating and resetting including > Selling account Managed Payments setup before listing ... Recheck using a PC/Laptop >
https://www.ebay.co.uk/help/account/changing-account-settings/changing-account-settings?id=4193
https://www.ebay.co.uk/help/selling/getting-paid/introducing-managed-payments-ebay?id=4795&st=12&pos...
