Cannot be reproduced with all NVME drives, but my drive is a Samsung 970 EVO 256GB.
Excepted outcome is system shutdowns successfully, without a kernel panic. My system kernel panics, THEN shuts off. Happens on every Linux distro and is an upstream problem with Linux. However it's persisted for quite some time and I haven't found any progress recently on it so until they fix it I was wondering if a patch could be brought in, I compiled Solus' kernel a little while ago with this patch and the panic went away.

Has been happening for a pretty long time, wasn't going to submit anything besides I understand it's better to submit upstream but it's been long enough that I'm not sure when that will happen. Until then I think a small patch is fine, and when it's fixed upstream it can be removed.

https://lists.infradead.org/pipermail/linux-nvme/2019-April/023258.html