21.04 Panics attempting to boot 5.10.0-3.4 in gcp EFI disk

This was caught while testing a few runs in the google cloud.
Steps to reproduce:
1.) deploy 21.04 in the cloud (n1-standard-1 instance type)
2.) install 5.10.0-3.4 from the canonical-kernel-team bootstrap ppa
2a.) sudo add-apt-repository ppa:canonical-kernel-team/bootstrap
3.) sudo apt install linux-generic-wip
4.) update grub to boot the generic kernel as the default kernel will be -gcp, (use attached script comment#4) ./script.sh generic
5.) reboot and monitor console logs

Full startup logs attached:

looks to be grub related, I have not looked into this any further.

   1.410153] VFS: Cannot open root device "PARTUUID=02631d3d-a298-4349-b157-aa86d82843b5" or unknown-block(0,0): error -6
[ 1.411882] Please append a correct "root=" boot option; here are the available partitions:
[ 1.413203] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[ 1.414356] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.10.0-3-generic #4-Ubuntu
[ 1.415702] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[ 1.417180] Call Trace:
[ 1.417710] show_stack+0x52/0x58
[ 1.418263] dump_stack+0x70/0x8b
[ 1.418738] panic+0x101/0x2e3
[ 1.419209] mount_block_root+0x21e/0x298
[ 1.419778] mount_root+0x38/0x3a
[ 1.420243] prepare_namespace+0x13f/0x18d
[ 1.420840] kernel_init_freeable+0x156/0x17d
[ 1.421574] ? rest_init+0xba/0xba
[ 1.422135] kernel_init+0xe/0x116
[ 1.422708] ret_from_fork+0x22/0x30
[ 1.423858] Kernel Offset: 0x10c00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[ 1.425374] ACPI MEMORY or I/O RESET_REG.