Why does pipe keep reading from a Readable Stream if the buffer is full?

Question

Node.js

Good afternoon,
there

Readable Stream

class MyReader extends Readable {
  current = 0;
  max = 100;
  _read(size) {
    this.current++;
    if (this.current >= this.max) {
      this.push(null);
    } else {
        const buffer = Buffer.from(`${this.current}`, 'utf8');
        const couldBeAdded= this.push(buffer);
        console.log(`push: ${this.current}, done: ${couldBeAdded}`);
      }
    }
}

There is also

Writable Stream

class MyWriter extends Writable {
  _write(chunk, encoding, done) {
    setTimeout(() => {
      console.log(`chunk: ${chunk.toString()}`);
      done(); // торможу запись
    }, 100);
  }
}

I pass it a Writable Stream:

const read = new MyReader({ highWaterMark: 4 });
const write = new MyWriter({ highWaterMark: 4 });
read.pipe(write);

As a result, in the console at iteration 10 (when I try to push stream 10) read.push() returns false, which means that the buffer is full, and further pieces will fill the memory.

When read.push() is false, the stream's Readable buffer is full , but pipe doesn't pause reading and wait for the buffer to be freed, why?

In the opposite situation, when the Writable Buffer is full, pipe pauses reading, everything is clear here