I have a fairly simple static website pipeline with Hugo. The main branch has the code, on each push I run the following GitHub Workflow to generate the website and push it to gh-pages branch. Unfortunately, every time a push happens, the “Custom domain” in “Settings” → “Pages” gets reset to an empty one and my website is deployed to username.github.io/project-name, so I have to get back to this setting every time I push some changes. This is extremely inconvenient, why exactly is this happening? Can I stop it from happening in the future?

Here’s what my Workflow looks like.

name: Build and deploy
on:
  push:
    branches:
      - main
jobs:
  build:
    name: Build & deploy to GitHub Pages
    runs-on: ubuntu-20.04
    steps:
- name: Check out code
  uses: actions/checkout@v2
  with:
    submodules: recursive
    fetch-depth: 0

- name: Setup Hugo
  uses: peaceiris/actions-hugo@v2
  with:
    hugo-version: 'latest'

- name: Build website
  run: hugo --minify

- name: Deploy
  uses: peaceiris/actions-gh-pages@v3
  with:
    github_token: ${{ secrets.GITHUB_TOKEN }}