@esparzab VMSA-2021-0020 is applicable only for vCenter Server, so patching ESXi is not required to address this vulnerability.
If you have a vCenter Server, please patch to the latest version released for this VMSA, step-by-step procedure to patch vCenter Server is available in below community link:
https://communities.vmware.com/t5/vSphere-Upgrade-Install/tkb-p/2015