if clean boot fixes it, it shows its likely a startup program. You should, over a number of startups. restart the programs you stopped to isolate the one that is to blame.
update: this didn't go to plan, I managed to disable the login with pin service and now it's asking for a password which I managed to login once with but not again and now I'm locked out of my account and can't do anything
any idea how I can reset my password as I have important data I need so can't reset the laptop