Hi,
thank you for the report! I can reproduce the issue here and will look into it. It's a regression from the switch to the QEMU -blockdev command line with machine versions >= 10.0. We accidentally use the throttled block node as the source of...
If you have a Proxmox subscription for the affected servers, you should create a support ticket, the support staff at proxmox is usually very helpful.
Apart from this, if your boss is indeed a "mean" guy, then maybe you should tell him not to...