I came across the same issue after I finished building the whole site and realized that I never tested production.
The error seems to be that the purge arguments are set relative to the tailwind config, while it should be relative to the root folder. I am not sure if this is only a Windows/WSL problem, though.
So this fixed it in tailwind.config.js
:
purge: [
'./app/**/*.php',
'./resources/views/**/*.php',
'./resources/assets/scripts/**/*.js',
],