With kernel 6.3.2-1 installed on Dom0 I was having issues where my appVMs froze for a couple of minuets after resuming from suspend. I was able to resolve the AppVMs being frozen for a couple of minutes by downgrading the AppVM kernel (not the sys-vms or Dom0) to 5.15.103-1.
I did this in the qubes manager, by right clicking the appVM and clicking settings. On the “advanced” tab, choose the kernel version.
I also had to enable “linux s3” in the UEFI to get susepend to even work in the first place.