Some apps read from a service that needs a login. Rather than pasting a token into every app, you connect the service once for the workspace and the apps use that connection.
What changes
An app backed by a connected service shows you your own things instead of a credential field. The Power BI app offers your reports; the Grafana app offers your dashboards; a calendar app offers your calendars.
The access token itself is handled behind the form and never rendered. There is nothing to copy, nothing to paste, and nothing to rotate by hand in each app.
Which services
Salesforce, Airtable, Power BI, Grafana, Google Calendar, Outlook Calendar, and Slack.
Connect them under Settings, then Integrations. Owners and Admins can connect them, and the connection is then available to everyone in the workspace. See Connecting an integration.
When an app stops showing data
Usually the connection rather than the app. A revoked authorization, a rotated credential on the provider’s side, or an expired grant all present the same way: the app installs fine and shows nothing.
Check the integration first, before reinstalling the app.
When there is no integration
An app can still ask for a credential directly, as a secret. That is the right route for a service we do not have a built-in connection to.