@De Cock -
Sorry I couldn’t provide more detail in my comments earlier..I was sidetracked with a couple other things at the time 😊
Basically, the Hyper-V link you shared is the same as the vSphere link I shared just above. You are spot on for retention. VDC is Azure underneath the hood, and thus Cloud-based Object Storage. Both HV and VMW Guides link to the Object Storage Immutability sections which discuss retention for Immutability.
The section in the link discusses “Actual Retention”:
https://helpcenter.veeam.com/docs/backup/hyperv/hiw_immutability_os.html?ver=120#object-storage-actual-retention , which references Block Generation and how it’s added & used for actual immutability retention:
Actual retention = job retention policy + immutability period + Block Generation period
So for example, whatever you configure for the Job, add the Immutability period, then an additional 10 days (non-AWS or IBM Cloud storage) for Block Generation and that is your immutability period.
I get that you’d like the VDC section of the Guide to explicitly state that...I’m the same way 😊 But, that area just references the Object Storage immutability sections by placing links in its section so as to not duplicate text is my guess.
Hope that better explains.