According to this: https://learn.microsoft.com/en-us/mem/configmgr/core/clients/manage/monitor-clients#about-client-status
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- Client activity: The site considers the client as active if it has communicated with Configuration Manager in the past seven days. The site considers the client inactive if it hasn't done the following actions in seven days:
- Requested policy update
- Sent a heartbeat message
- Sent hardware inventory