[Fagottino89]

That’s not how it works (at least for the monitors I know). If you connect your monitor to the computer they won’t be able to see anything, if they could see your OS and versions and stuff, it would be a violation of privacy, as you’re never asked to share any information with them. Moreover, the monitor is an output device, and there shouldn’t be any way for dell too see that is connected to a computer and is working etc.
Very different story if we are talking about a laptop or a different type of device that can be connected to internet .

Also very different story if they also ask you to share some reports of the devices connected to your computer.

Finally a monitor could be connected to a computer but still not show anything

This is what I had always assumed as a monitor is an output device.

That's what I thought. But his line of questioning took me by surprise and suggest that at the very least he had some information on hand.

He started by asking me for some information which including the name, email and phone number registered to the monitor. I made that up.
He took his sweet time "checking a few things" which was vaguely unspecific.

Then he asked which system was it connected to. I said it wasn't connected to anything now. He repeated the question but being more specific this time, leaving me with the choice of dell laptop or apple laptop. At which point I was on high alert. Did he have access to the device connected to the monitor? How's that possible? Or maybe he simply sees whether it is connected, which is feasible for tech to troubleshoot a device but I thought you would need to ask for permission or it'd be a violation of privacy.

But then again maybe the monitor sn I found had a deal with dell to provide such services.

After another weirdly specific question, I made an excuse and bolted out of there.

It was bizarrely difficult for something I thought would be easy to get an RMA.

The item in question was DELL 34.1"U3421WE IPS 21:9

The monitor you trying to SE can be connected to the internet thats why he knows all the stuff and asked for a verification

That changes the whole scenery. Of course they can see everything if you connect it on internet