In the CloudSOC Notification area, there is a message: "Expired Salesforce Refresh Token for Tenant:tenantID, Account: accountID". There is also no activities to be found for this specific Salesfroce account.
Your Salesforce admin has placed a refresh token policy that expires after a fixed amount of time.
Please deactivate and then reactivate the Salesforce Securlet for this Salesforce instance. If needed, connect with the company's Salesforce admin to extend this timer or change the policy to "valid until revoked".