which raises one of the weirdest behaviors of the HN system (at least for me)

I second that. Two months ago I tried to submit what I found to be a quite interesting video from 2018 and it was immediately marked as duplicate:

https://news.ycombinator.com/item?id=40798566

Checking past submissions, I saw that the last time it had been submitted was a year ago:

https://hn.algolia.com/?dateRange=all&page=0&prefix=false&qu...

But then, as you can see from that page, someone resubmitted the video a month ago and for some reason that one got through.