A built-in timer may be set to automatically close sessions if no keyboard or mouse activity is detected for a short period.
TeamViewer has a built-in auto-disconnect for idle sessions. By default, it's longer than 1 minute, but a policy or setting might have changed it. teamviewer times out after 1 minute
Run this to pinpoint the cause:
If you are using a company-managed TeamViewer account, an admin may have set a of 60 seconds. A built-in timer may be set to automatically