This is not an upgrade blocker. This is an incorrect warning message and that is being rectified in future releases.
Image Compliance scan shows 'The CPU on the host is not supported by the image' even though the CPU in use is shown as supported in the VMware Compatibility Guide.
As a general practice, CPU which might not be supported in future releases are marked as deprecated.
Due to an internal error, warnings for deprecated CPUs are being shown as unsupported CPUs warnings instead.
VMware is aware of this issue and working to resolve this in a future release.
The message 'The CPU on the host is not supported by the image' is a warning. If the CPU is still supported, you can safely ignore this warning and proceed with remediation. The remediation shall not be blocked due to this warning message.