Welcome to the Community,
you may need to update to the current ESXi patch to reslove this issue.
from VMware ESXi 6.7, Patch Release ESXi670-202006001
PR 2560750: vSphere Client might display false fan health sensor alarms on HPE Gen10 Servers
In the vSphere Client, you might see fan health as Critical on HPE Gen 10 servers after upgrading an ESXi host to ESXi670-202004002. This alarm is identified to be false positive.
This issue is resolved in this release.
André