Tim, all these signs are telling me you've already quit your job. You just haven't made it formal yet.
I recognise all these signs in myself in my very first job 18 years ago now. I was also too scared to quit. In the end, the decision was made for me when HR told me to pack my bags and go home.
My biggest regret from that time was not telling my manager that I hated my job and I wanted out. He put a lot of effort in encouraging me when I was on a performance improvement programme. I realise now that I was wasting his time, and mine, for not stepping up and doing what my heart was telling me.
You're already dead, brother. Stop being a ghost and move on to the afterlife.