An Azure service that is used to manage and protect cryptographic keys and other secrets used by cloud apps and services.
anonymous user, thank you for reaching out. We usually do recommend using a separate Key Vault specific to each Resource Group in terms of Azure Resources, to make it easier for maintenance.
If VMs are placed in separate resource Groups, its advisable to add one Key Vault per Resource Group to maintain the VMs disks present in that specific Resource Group.
Hope this helps.
Do let us know if this helps and if there are any more queries around this, please do let us know so that we can help you further. Also, please do not forget to accept the response as Answer; if the above response helped in answering your query.