Sadly, no, we only keep the past 3 images around as we would otherwise very quickly run out of disk space on the image servers…
In our own test systems, the workaround I used was to manually download the old centos8 kernel and forcefully install that, then prevent the system from ever updating it.
This isn’t really a solution I’d recommend though as that means you’re not getting security updates either. In our case, those test VMs are completely disconnected from the internet, so it’s not a problem, but for anyone else, that would likely be an issue…
We are looking at using virtiofs in the future, though it’s unclear that this would be supported any better on the centos8 kernel…