v5 Regression react-error-overlay build - Uncaught ReferenceError: process is not defined

Created by: dev-bjoern

I use following command to start: npm run start

Then, whenever I save a file, I get the following "Uncaught ReferenceError: process is not defined" error in the browser console.

VM27:2 Uncaught ReferenceError: process is not defined
    at Object.4043 (<anonymous>:2:13168)
    at r (<anonymous>:2:306599)
    at Object.8048 (<anonymous>:2:9496)
    at r (<anonymous>:2:306599)
    at Object.8641 (<anonymous>:2:1379)
    at r (<anonymous>:2:306599)
    at <anonymous>:2:315627
    at <anonymous>:2:324225
    at <anonymous>:2:324229
    at HTMLIFrameElement.e.onload (index.js:1)
4043 @ VM27:2
r @ VM27:2
8048 @ VM27:2
r @ VM27:2
8641 @ VM27:2
r @ VM27:2
(anonymous) @ VM27:2
(anonymous) @ VM27:2
(anonymous) @ VM27:2
e.onload @ index.js:1
be @ index.js:1
he @ index.js:1
tryDismissErrorOverlay @ webpackHotDevClient.js:184
onSuccessfulHotUpdate @ webpackHotDevClient.js:150
handleApplyUpdates @ webpackHotDevClient.js:257
(anonymous) @ webpackHotDevClient.js:276
load (async)
be @ index.js:1
he @ index.js:1
tryDismissErrorOverlay @ webpackHotDevClient.js:184
onSuccessfulHotUpdate @ webpackHotDevClient.js:150
handleApplyUpdates @ webpackHotDevClient.js:257
(anonymous) @ webpackHotDevClient.js:276
Promise.then (async)
tryApplyUpdates @ webpackHotDevClient.js:271
handleWarnings @ webpackHotDevClient.js:147
push../node_modules/react-dev-utils/webpackHotDevClient.js.connection.onmessage @ webpackHotDevClient.js:210

react-scripts 4.0.3 npm 6.14.8 node v14.18.1 FreeBSD 12.2-RELEASE-p4 GENERIC amd64

The project compiles just fine, but the hot reloading seems to be erroring.

I have no problem with react-scripts 3

Isnt process a node environment variable? How does it end up in the browser?