Okay... so...
it's fixed, the Wayland vs X11 issue reminded me about some issues I recalled about the switchable graphics, so I attempted to disable it... which I did by editing my GRUB as such:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash intel_iommu=igfx_off"
and we're all good! Radeon kernel driver is being used, everything is rendering properly and I can now enjoy my new Zorin update! Whew... (even re-enabled Wayland just for good measure).