stream/iter: toReadableSync() drops chunks after backpressure

[trivikr]

Version

26.1.0

Platform

macOS 26.4.1 (25E253)

Subsystem

stream

What steps will reproduce the bug?

import { toReadableSync } from 'node:stream/iter';

function* gen() {
  yield [
    Buffer.from('a'),
    Buffer.from('b'),
    Buffer.from('c'),
  ];
}

const readable = toReadableSync(gen(), { highWaterMark: 1 });

readable.on('data', (chunk) => {
  console.log(chunk.toString());
});

readable.on('end', () => {
  console.log('end');
});

To run it

node --experimental-stream-iter repro.js

How often does it reproduce? Is there a required condition?

Always.

What is the expected behavior? Why is that the expected behavior?

a
b
c
end

What do you see instead?

a
end

Additional information

No response