Thank you to Aiber for coding the patch (it’s a variant on an old Threadripper fix for the same issue), and thank you to tkoham for posting said fix here on the forums. There is finally a kernel patch that worked for me in both boot and reboot, and it needs no editing.
Patch link here: https://clbin.com/VCiYJ - copy text from link and save as pci.patch file, then apply the patch to kernel. Look up how to compile a kernel / patch a kernel for your respective distro. It’s highly recommended that you use your distro’s package manager method of compiling a kernel.
There is no editing of the patch required as it appears to be a universal fix. I can’t say for certain that it will work for everyone. Post any problems here.