Universal containers (UC) has a mobile application that calls the salesforce REST API.

The most likely cause of the issue is that the refresh token expiration policy is set incorrectly in Salesforce. A refresh token is a credential that allows a connected app to obtain a new access token when theprevious one expires1. The refresh token expiration policy determines how long a refresh token is valid for2. If the policy is set to a short duration, such as 24 hours, the users have to enter their credentials once a day to get a new refresh token. To prevent this, thepolicy should be set to a longer duration, such as “Refresh token is valid until revoked” or "Refresh token expires after 90 days of inactivity"2.