Thank you so much, @Aravisian ! I got an answer from Zorin support right about the same time as you, and that was the solution!
I don't quite get why a more recent kernel doesn't work, but I suppose that's why LTS kernels exist as well.
In short, here's what I did:
sudo apt install --install-recommends linux-headers-5.8.0-63-generic linux-modules-5.8.0-63-generic linux-modules-extra-5.8.0-63-generic linux-image-5.8.0-63-generic linux-generic
Then I removed nomodeset from /etc/default/grub, ran sudo update-grub, rebooted, pressed Esc, chose advanced settings, chose the 5.8 kernel, and all was fine!
I then removed the other more recent kernel I had:
sudo apt remove linux-headers-5.11.0-38-generic linux-image-5.11.0-38-generic linux-modules-extra-5.11.0-38-generic
For reference, the output in the commands above, now:
$ uname -r
5.8.0-63-generic
$ sudo lshw -c video
*-display
description: VGA compatible controller
product: Intel Corporation
vendor: Intel Corporation
physical id: 2
bus info: pci@0000:00:02.0
logical name: /dev/fb0
version: 01
width: 64 bits
clock: 33MHz
capabilities: pciexpress msi pm vga_controller bus_master cap_list rom fb
configuration: depth=32 driver=i915 latency=0 mode=2880x1800 visual=truecolor xres=2880 yres=1800
resources: iomemory:600-5ff iomemory:400-3ff irq:153 memory:601c000000-601cffffff memory:4000000000-400fffffff ioport:3000(size=64) memory:c0000-dffff memory:4010000000-4016ffffff memory:4020000000-40ffffffff
$ inxi -G
Graphics: Device-1: Intel driver: i915 v: kernel
Display: x11 server: X.Org 1.20.11 driver: fbdev unloaded: modesetting,vesa resolution: 2880x1800~90Hz
OpenGL: renderer: Mesa Intel Xe Graphics (TGL GT2) v: 4.6 Mesa 21.0.3
Thanks again!