The way their spam system works for these kinds of things is that it’ll still appear normally to you when you look, but it’s invisible to everyone else. It’s similar to shadowbanning. This way the supposed “spammer” thinks they’ve succeed and does not attempt to take countermeasures.
Try looking in the fiat500 subreddit when logged out or in incognito mode and you’ll see what I mean. Users can go to your post through a direct link, but it won’t show up in the subreddit’s feed. It’ll also have an unusually low view count. In the image below, you should notice that your post doesn’t show up in the feed of new posts.
If you want something more conclusive, here’s a comparison of some of my posts in /r/Photogrammetry, where I first noticed the issue. The “Patapan” model, submitted using the long link is the only one that shows up. The short link versions above and below the “ADAM - Behind the Scenes” video are missing, but only when I’m not on my account.