VMWare side channel

[TECH198]

I realize this may be alerting users to performance issues :

Virtual Machines with side channel mitigations enabled may exhibit performance degradation:-

https://kb.vmware.com/s/article/79832

Why is it only in Big Sur,.,.. Its doesn't show in Catalina..  Why?  

[ColoradoMarmot]

I suspect it's that in Catalina Fusion still uses it's own hypervisor, while on Big Sur it uses apples.