SentinelOne device icon is displayed in red, if there is some pending action required for SentinelOne to become fully functional.
This includes any of the following:
Agent Suppressed (macOS only) - An agent upgrade might be required.
Unprotected (macOS only) - Enable the anti-tampering for the agent, or make sure that the agent's local configuration is appropriate.
Incompatible OS (macOS only) - An agent upgrade might be required.
Attention Needed (Windows only) - Reboot the endpoint manually.
Missing Permissions - Make sure that the user permissions on the endpoint computer allows SentinelOne agent installation.
Reboot required.