There was a bug in KDE Plasma that would cause it to sometimes not shutdown all processes it started when you shutdown while still being logged in.
This would result in an extra 150 second delay (I think, might have been 90) where you wouldn't see any output unless you had some extra systemd and kernel logging visible. If you had those parameters enabled you would see that systemd was waiting for SDDM (which starts Plasma) to exit which it would never do until it hit a timeout and was force killed.
This is fixed in Plasma 5.24 which has not yet hit the repos. It is also possible to log out of Plasma and then shutdown from SDDM which would bypass the issue.
If anyone is interested in permanently enabling the debug logging to see what the kernel/systemd are doing in the background you can create the file /etc/kernel/cmdline-removal.d/quiet.conf with the following contents:
quiet
splash
systemd.show_status=false
loglevel=3
and then run sudo usysconf run -f. This will ensure that the "quiet" boot flags are removed from all Solus boot entries and that they will not be added back on future kernel updates.
@ArnavGupta Honestly if you don't want to deal with figuring out the boot rescue stuff (which you should as it's a very useful thing to know) the fastest way to get back to a working system is to mount your system drives, copy all of your data to a usb hard drive or similar, and then reinstall the OS.
