Getting ‘The current user cannot perform operations on cart’ error while using Magento’s GraphQL API via Remix.run. How to resolve?

I am currently building a storefront using Magento 2 and Magento’s GraphQL API via Remix.run. However, when a customer tries to log in, they receive the error message: The current user cannot perform operations on cart 'XXXXX'. I am unsure what is causing this error and would appreciate any help or advice on how to resolve it. Thank you.