turn-off error obfuscation in production for server actions on Vercel

Locally everything is fine, when deployed to Vercel, backend runtime errors are trapped by Vercel/Next.js and they are automatically obfuscated, which is nice, but I want to turn it off.

unfortunately it seems that setting the following env var didn't change anything:

NEXT_PUBLIC_DEBUG_ERRORS=true

to reproduce this problem:

server action throws error, for example:

'use server';

export async function throwRegularError() {
  throw new Error('this is a regular error: "dd-trace-8278-cab9522e6e28"');
}

in production (on Vercel at least), the client will see this:

Caught error from 'throwRegularError': {
  "name": "Error",
  "message": "An error occurred in the Server Components render. The specific message is omitted in production builds to avoid leaking sensitive details. A digest property is included on this error instance which may provide additional details about the nature of the error.",
  "stack": [
    "Error: An error occurred in the Server Components render. The specific message is omitted in production builds to avoid leaking sensitive details. A digest property is included on this error instance which may provide additional details about the nature of the error."
  ]
}

As a side-note, technically this is wrong

An error occurred in the Server Components render

it should read this instead:

An error occurred in a Server Actions call

https://github.com/vercel/next.js/issues/78573