I managed to resolve that. For those who are interested here is the solution:
Install gdisk with the following command:
brew install gdisk
After that, run gdisk passing the disk that has the FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF.
sudo gdisk /dev/disk3
Then you will be prompted with the following questions. Answer like I did below.
Command (? for help): t
Single user mode is there in order to be able to diagnose and fix problems with the system. It is commonly used if there's an error with the system that prevents it from properly booting normally into multiuser mode (i.e. the default mode).
The single user mode allows advanced users to examine the file system, change settings, and otherwise work with the ...
What you suggest is no longer possible with Big Sur. When booting to Recovery, you are required to enter a password of an existing account. AFAIK, these passwords are not stored in the Recovery volume. This would make it impossible to boot from a standalone Recovery disk.
Before Big Sur, there is no reason the an AFPS Recovery volume could not be placed on a ...
You seem to have booted into an older version of macOS Recovery (there's an item called "Install OS X Yosemite.app" visible in your screenshot). This is something that can happen with Internet Recovery, depending on the Mac model and OS version.
If you use the regular local Recovery (⌘ R), the spctl command should be available.
If you HAVE to use ...
Wait for Internet recovery to finish loading, proceed with normal steps.
P.S. this shouldn't be necessary unless you've enabled the option to disallow booting from external media. If that is the case, see this article for instructions: https://support.apple.com/en-us/HT208198#open
If you're impatient like me, go to System Preferences > ...
Bootcamp partitions require you to use Bootcamp Assistant (same tool you used to create a Bootcamp partition) to remove them and the associated Windows assets:
As Apple says "WARNING: Do not use any other utilities to remove Windows or a ...