I am too using the tailwindcss v4 with NgPrime. soo i got fix by adding this line to the angular.json file at style section.

"styles": [
"src/styles.scss",
"./node_modules/tailwindcss-primeui/v4/index.css"
],

and style scss file should look like this.

@use 'tailwindcss';
@use 'primeicons/primeicons.css';

as you can see i am using @use because @import can't be use after new ruleset for scss or sass.It is working for me.