In my case I needed a combination of some answers here.

First, having config.assets.debug = true in the config/environments/development.rb file.

Then, I needed plugin :tailwindcss if ENV.fetch("RAILS_ENV", "development") == "development" on the puma.rb file. This way it runs the application and runs Tailwind running on "watch" mode.

I have ruby 3.3.4, rails 7.1.5 and node 20.18.0 versions.

See https://stackoverflow.com/a/78393579/12955733 and https://stackoverflow.com/a/78250287/12955733.