Strange noise Samsung Ecobubble on rinse

Normally a noise that happens on the rinse cycle is caused by something rattling around inside the drain pump. Does the noise happen when the washing machine is draining the water, or does it happen while it is actually rinsing the laundry? However, the way you describe the sound, it doesn't sound like the classic something rattling around the pump noise. If you don't think it is something to do with the pump the first thing to do is to disconnect the washing machine from the mains, and then take off the lid and start moving the main outer drum around.

Push it forward and backwards, up-and-down, side to side. This will check if there is anything wrong with the suspension or the chassis. After that, the only thing that could be done is to listen to the sound with the back panel and lid off, which is obviously not recommended unless you know exactly what you are doing, and never leave a washing machine unattended in that state in case someone touches something inside. Only by observing the noise and locating it with your ears can you find out what is causing the noise. I have an article with tips and advice about how to troubleshoot a noisy washing machine