Ultimately, all the datasets on Steam are scraped one way or another, since Steam themselves don't seem to publish it. I could be that they simply never came across your project before you delisted it, and of course after delisiting it I don't think they'll ever come across it.
Hm yeah. We removed it a few years ago now so I assume they should have found it though. We followed these instructions and had to contact valve and give a justification https://partner.steamgames.com/doc/store/retire_app I don’t remember the details of the form but maybe there were options and one amounts to being delisted and another amounts to just no longer being visible and available for sale.
"Deslisted" == "no longer being visible". If it's delisted it won't show up in search results, tag listings and more. So if you just had it online for a few weeks, that was the only moment the scrapers could find it. If they didn't catch it at that point, they'll never catch it.
