Your Windows 10 virtual machine will be updated and not possible to downgrade since VMware updates the virtual machines with the latest compatibility by default settings. In case you want to revert to Mojave at any point and maintain your latest working Windows 10 virtual machine, you should look into either; backing up the whole of your virtual machine by duplicating it and keeping that duplicate safe and never use it with Monterey. Then use the other one.
Or change the hardware compatibility to something that will fit VMware 11.5 - such as 16
Currently we're at 19 and VMware Fusion 12 starts at hardware compatibility 17 - after that you'll have to work around a lot of things to revert that single virtual machine that you didn't backup and keep safe to something that will work with Mojave again.
That's why I suggest making a duplicate and keeping it out of the
Virtual Machines.localized - folder
For keeping a complete backup of Mojave 10.14.6 you'll have to use CarbonCopyCloner or the built-in Time Machine - Time Machine is your best bet here IMO.
Now you'll just have to understand that while you
can revert to macOS Mojave after being on Monterey for a while. Just know that your absolute best installation process is to get a hold of Mojave from Apple and create a USB installer to then use to completely wipe out Monterey as Monterey will update your system drive with additional APFS containers.
For that to go away and you have a perfect Mojave installation again. You should clean install and then use your existing Time Machine backup to manually drag out your stuff from.
It's what I do normally when I revert. I'm not going back and forth as much anymore. I think I've settled quite well with Monterey. It was scary to let go of LiteIcon and my purchased games and the macOS appearance(I make new themes so not a big deal)
It might be a tough transition for you too? Give it time.
This screenshot shows what I mean by Hardware Version compatibility - It appears that you can keep using Hardware Version 16 for Fusion 12.2.x
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