That sounds like a terrible experience. At first glance it also sounds like a hardware issue but updating anything with an Ubuntu base was always painful to me.

It would help if you gave a little bit more info (like logs), without it, this is my blind guess:

• 1, 2 points to a storage drive on your system
• 5 points to your system drive specifically, that some parts of the drive are failing. Although I would expect that to happen with HDDs, not SSD
• 3 has logs, you can switch to the detail screen during the shutdown splash by hitting Esc? Or maybe a different one on Ubuntu, don’t remember. Should tell you which service doesn’t want to stop (and if it’s always the same one, if you check multiple times)
• As for 4 and 6…I cannot fathom how is that happening

Every time someone posts about systemd I just paste in the link to the Tragedy of systemd video https://youtu.be/o_AIw9bGogo and move on