The post looks fine to you. That's the problem.
When a post is filtered or removed, it stays visible in your own feed and on your own profile. The only way to know is to look at it the way a stranger does — signed out. PostGuard does that for you, on a schedule, and tells you when the answer changes.
Four checks over 24 hours
At 5 minutes, 30 minutes, 2 hours and 24 hours, your post is fetched without your session and compared against the community's public new list. Most filters fire in the first hour; some fire much later.
Four honest states
Visible, removed by moderators, reachable but missing from public listings (the filter queue), or not confirmed. Being rate-limited is never reported as a removal — one false alarm and the feature is worthless.
Account-level, not just one post
One post disappearing is a community decision. Everything disappearing is an account problem. The full check samples your recent posts plus your profile page and only calls it a shadowban when the evidence is account-wide.