[object Object] is not a PostCSS plugin

[dustinhorton]

"postcss-100vh-fix": "^1.0.0",

used via:

"gatsby-plugin-sass": "^2.3.13",

[…]

const autoprefixer = require('autoprefixer')
const postCss100VhFix = require('postcss-100vh-fix')
const postCssDiscardDuplicates = require('postcss-discard-duplicates')
const postCssFlexbugsFixes = require('postcss-flexbugs-fixes')
const postCssFocus = require('postcss-focus')

[…]

module.exports = {
  […]
  plugins: [
    […]
    {
      resolve: 'gatsby-plugin-sass',
      options: {
        cssLoaderOptions: {
          camelCase: false,
        },
        postCssPlugins: [
          autoprefixer(),
          postCss100VhFix(),
          postCssDiscardDuplicates(),
          postCssFlexbugsFixes(),
          postCssFocus(),
        ],
      },
    },
   […]

no such error before adding postcss-100vh-fix.