Approx. after Sept. 6th 2021, if you updated your copy of Zorin OS 16 and got the 5.11.0-34 kernel, you may experience black screen on logging in. This may primarily affect Nvidia users.
Boot into the Recovery Menu by tapping or holding the
left shift key at boot.
Advanced Options for Zorin, select to boot from the working 5.11.0-27 Kernel.
Getting reports that initially, updating the Graphics drivers allows the 5.11.0-34 kernel to work - but then it crashes later.
The best option is to stick with the 5.11.0-27 kernel at this time.
You can lock the kernel to prevent it updating with:
sudo apt-mark hold linux-image-generic linux-headers-generic
Unlock it with:
sudo apt-mark unhold linux-image-generic linux-headers-generic
Further reports that this affects Suspend function. Confirmed on Linux Mint with Nvidia Drivers 470, 460 and 465, as well.