Not sure what's changed but I'm observing some strange behavior with the 4.0 kernel on Havoc 3.5 GSI.
While I can get to the lockscreen much earlier compared to previous kernel versions, the system is not stable at this point and SystemUI would crash (back to Havoc logo) 1-2 times before going stable.
And during one of those abrupt soft reboots my exFAT SD card got fscked up (Issue with SD card, tap to fix which in turn prompts me to format it). Fortunately I'm able to fsck it back to life from TWRP.
The issue is minor, as aside from this instability during system startup the kernel's running mostly stable.
EDIT: I think there might be something like race conditions going on. I'm able to record a logcat of the boot process (this time after flashing an updated GSI it soft-rebooted 2 times during the boot). However, the log content is quite messy and I'm yet to find out anything that might be interesting...
EDIT 2: It seems if I wait for at least 2-3 minutes before unlocking the phone, I could avoid the soft reboots. Probably with this kernel some things finished their initializations too early.