One word, two very different failures
Shadowban is a community word, not an X feature. It covers at least two different failures: your posts stop appearing in search and suggestions, or your replies stop being visible to people who do not follow you. The difference matters, because each one shows up in a different test and often clears on a different schedule.
A third and much milder case gets mixed in: your reply is visible but ranked so low that almost nobody scrolls to it. That is a ranking outcome, not a hidden reply, and it is the most common false positive.
Search ban: invisible to discovery
In a search-level restriction, your account and posts stop appearing in search results and type-ahead suggestions for people who do not already follow you. Followers keep seeing your posts in their timeline, so the account looks completely normal from the inside.
Two variants are commonly reported: suggestions only, and suggestions plus results. The suggestions-only version is the milder one, and it is usually what the phrase search suggestion ban refers to.
Reply ban: invisible in conversations
In a reply-level restriction, your replies do not render for logged-out visitors or for accounts that do not follow you. The conversation keeps moving without you, which is why creators notice this one first — it removes the discovery path most people rely on for growth.
Because replies are also publicly ranked, the honest test is not whether you can see your reply, but whether a stranger can. Logged out, not logged in.
What usually comes next
The two can appear together and can lift at different times, so a scan reports the four checks separately instead of printing one verdict — a combined restriction and a single failing check call for different responses.
Whatever you find, the response starts the same way: stop the behaviour that plausibly triggered it, keep posting normally, and re-measure in a few days instead of refreshing every hour.