Could you start a bisection maybe?
I for one am having two issues here.
The harmless one is that I'm lacking a cooler for the RPi and my cross compiling skills have become a bit rusty. Both could be fixed quickly, of course.
The not so harmless one is that kernel 5.18.x is completely unusable due to an other regression: the SD card is slow to a degree that makes it rather unusable, rather simple tasks are tainting the kernel because of this. E. g. a simple kernel update takes half an hour on 5.18.x. Neither sure what's the culprit here nor how to deal with it.
Nonetheless: Could the module be installed without updating the kernel as a whole, e. g.by DKMS? Is there a way to narrow down the commits in question, e. g. something like 'git log ./drivers/gpu/drm/vc4/' in a Git checkout of the kernel sources?