Unknown error from PostCSS plugin. Your current PostCSS version is 8.3.0, but postcss-preset-env uses 7.0.36

You could be missing the .browserslistrc in the root of the project. If you pulled down from source control make sure whoever submitted the files originally remembered to include this file.

Deleting the node_modules folder and the yarn.lock file and reinstalling fixed the issue for me.

I think you need this pr https://github.com/csstools/postcss-preset-env/pull/211 to be merged.. then it should work.

There is a version mismatch in your postcss and the postcss version required by postcss-preset-env.

Or you could try downgrading your postcss.. but that will probably break everything else.