Disclaimer - this might be a duplicate of T3752
As I did some research I noticed that update-grub /etc/default/grub ignores GRUB_CMDLINE_LINUX_DEFAULT, so I went to /boot/grub/grub.cfg to see what actually got generated. Previous kernel (before todays update) and the current kernel had a slight different variable changes:
radeon.si_support=1 radeon.cik_support=1 amdgpu.si_support=1 amdgpu.cik_support=1
So even though YOU SHOULD BE VERY CAREFUL WITH THESE FILES I changed the first two variables to 0 (also tested to change and use update-grub, it changes the variables back to 1 again). I rebooted and vulkan works normally again.