Not every reach drop is a shadowban
Reach changes can come from recommendation eligibility, search filtering, content classification, audience fatigue, seasonality, ad restrictions, or ordinary ranking changes. Treating every decline as a hidden ban leads to the wrong fix.
The diagnostic compares multiple surfaces: logged-in and logged-out search, replies, recommendations, non-follower distribution, account-status notices, and recent account actions. The result is a practical cause tree rather than a promise of an invisible switch.