node_modules/@babel/plugin-proposal-private-property-in-object/lib/index.js

maybeWarn: try {
  var stackTraceLimit = Error.stackTraceLimit;
  Error.stackTraceLimit = Infinity;
  var stack = new Error().stack;
  Error.stackTraceLimit = stackTraceLimit;
  if (!stack.includes("babel-preset-react-app")) break maybeWarn;

  // Try this as a fallback, in case it's available in node_modules
  module.exports = require("@babel/plugin-transform-private-property-in-object");

  setTimeout(console.warn, 2500, `\
\x1B[0;33mOne of your dependencies, babel-preset-react-app, is importing the
"@babel/plugin-proposal-private-property-in-object" package without
declaring it in its dependencies. This is currently working because
"@babel/plugin-proposal-private-property-in-object" is already in your
node_modules folder for unrelated reasons, but it \x1B[1mmay break at any time\x1B[0;33m.

babel-preset-react-app is part of the create-react-app project, \x1B[1mwhich
is not maintianed anymore\x1B[0;33m. It is thus unlikely that this bug will
ever be fixed. Add "@babel/plugin-proposal-private-property-in-object" to
your devDependencies to work around this error. This will make this message
go away.\x1B[0m
  `);

  return;
} catch (e) {}

throw new Error(`\
--- PLACEHOLDER PACKAGE ---
This @babel/plugin-proposal-private-property-in-object version is not meant to
be imported. Something is importing
@babel/plugin-proposal-private-property-in-object without declaring it in its
dependencies (or devDependencies) in the package.json file.
Add "@babel/plugin-proposal-private-property-in-object" to your devDependencies
to work around this error. This will make this message go away.
`);