Strapi /admin gives 404 errors after redirect Nginx

url: env(“PUBLIC_URL” , "https://wp-admin.app/api”),

on your .env do you have a PUBLIC_URL env that is attached to it?
also when you update the config on server.js did you then build the strapi again

i recently ran into a similar issues

  1. admin image not showing as the URL is not set up properly → changing the url value via .env or the url in the server.js
  2. admin page itself loaded but blank and have 404 errors for the main.js as the URL pointed to the wrong path → Build the strapi again after changing configurations (maybe also have a look on the network tab to see if the 404)

hopefully, it could help you out, but im by no means any expert