postcss 7 installed by react-scripts 5?

[ripdog]

Hi all, I've been upgrading an old react app to modern packages. For some reason, after updating react-scripts to the latest, postcss only makes it to version 7, which throws errors when the server is started.

Here's npm explain:

>npm explain postcss
[email protected]
node_modules/postcss
  peer postcss@"^7.0.0 || ^8.0.1" from [email protected]
  node_modules/postcss-loader
    postcss-loader@"^6.2.1" from [email protected]
    node_modules/react-scripts
      react-scripts@"5.0.0" from the root project
  postcss@"^7.0.35" from [email protected]
  node_modules/resolve-url-loader
    resolve-url-loader@"^4.0.0" from [email protected]
    node_modules/react-scripts
      react-scripts@"5.0.0" from the root project

I was able to fix this by explicitly depending on postcss 8, but this isn't an ideal solution because I don't use it directly. I do have to use --legacy-peer-deps for an unrelated issue, is that the cause?