I went to check if the story I submitted today ( Breathing 101 — https://news.ycombinator.com/item?id=39227295 ) was present in the list, and it was indeed! I don't know how it reached the front page and why it got removed.
1. "Breathing 101" is an uninformative headline. I correctly guessed that it was literally referring to the human act of breathing, but it's still a bad title (I know it's not your title, and that HN encourages using the original source's title; it just sucks).
2. You submitted the link with no comment or context about what the article was or why it might be interesting. If a headline grabs my eye, I always click on the "N comments" link and the article link to open two tabs, and I look for additional descriptive text from the submitter, or a comment from them about what they found interesting. Sometimes I read the actual article first, but if the title is ambiguous or the topic is contentious, I'll usually start with the comments tab and see if I'm going to be wasting my time before I read an article. This alone wouldn't be a reason to downvote, but if I was leaning that way, it would factor in.
3. The word "wellness" in the link's domain is a huge red flag. To me it means "this is going to be a bunch of hippie crap". Not a primary factor, but seeing that would be enough to make me dig farther and find evidence so that I could Angry Downvote something I don't want to see on HN ever, if we could downvote. Yes, this is petty.
4. The very top of the linked article says "Click here to make an appointment". This indicates spam.
5. The article is just bad. There's not much information. It's not scientific. It touches lightly on some potentially interesting things but doesn't dive into them at all, or link to better sources, and it ends with what appears to be advice and encouragement to incorporate breathing exercises, but without much information about how or what the benefit is.
It looks like spam. It's the kind of clickbait that floods my Facebook feed.