Fixed it... For some reason I had provider: giscus in the YAML, which caused the following error in Vercel: duplicated mapping key in "/vercel/path0/_config.yml" at line 121, column -9:.

comments:
  provider: giscus # <---- culprit here
  giscus:
    repo: w-dib/w-dib.github.io
    repo_id: R_kgDONaq1kA
    category: Announcements
    category_id: DIC_kwDONaq1kM4Clp6n
    mapping: pathname
    strict: 0
    input_position: bottom
    lang: en
    reactions_enabled: 1

I need a coffee