After upgrading to 7.2.3 I saw the same problem with one of my VMs (the BAR 1: can't reserve .. messages) and when checking the dmesg output, I see the following two to three lines:
[ 0.000000] Command line: initrd=\EFI\proxmox\5.15.35-1-pve\initrd.img-5.15.35-1-pve root=ZFS=rpool/ROOT/pve-1...