Just make sure to take your time and let the monitor switch between different patterns so you can see if they're stuck constantly or rather "flicker" or disappear sometimes. You've got 7 days till you have to start DSR process and unless you have a cluster of dead sub-pixels, you won't be able to RMA the monitor anyway.
Dirt might be the cause of that black cluster, try cleaning it up a bit.
I agree, best not to take stance that Alfie presented in the other Hazro thread (any dead pixels/sub-pixels make the screen redundant).
Consider whether you really are bothered by them and if they are going to affect your work or getting enjoyable experience from using the monitor.
The resolution is enormous and it will be hard to notice dead pixels anyway. I'm quite experienced in searching for them as I always spend some time examining new monitors but I can't say most would bother an average user.