Kernel Panics in Catalina 10.15.4/Thunderbay 4
Actually, I think you ran into a macOS bug. MacOS bundles a promise driver. the kextcache may not have updated whne you installed the Promise new driver, causing the panic. Uninstalling SoftRAID reset the kextcache. We ran into this issue with kextcache's frequently and still do. When you update a driver, the newer driver should load reliably. Instead, too frequently, the extensions cache never updates to the new driver and keeps loading the bundled, older driver. This bug only exists with drivers bundled with macOS, as far as I know.
that would explain this panic, without assuming a driver conflict, which is unlikely.
The SoftRAID driver only loads when there is a SoftRAID disk connected. It is otherwise inert.
In addition, disks inside the promise box are hidden from macOS. the Promise box publishes a LUN to macOS, which is like a disk object, that has no disk format. Disk Utility would see an unformated disk object and initialize it like any new disk. that is why I believe the problem was the extensions cache.