PostEaseThe short answer
A shadowban refers to a platform reducing an account or post's visibility (hiding it from hashtag or search results, limiting how far it reaches) without notifying the account owner or removing the content outright. The account can keep posting normally, with no visible sign anything has changed.
Whether it "exists" depends on how strictly the term is defined
Major platforms generally deny using the specific term "shadowban," while separately acknowledging that their systems do limit the reach of content or accounts that trip certain automated signals, often without notifying the account. Whether that counts as a shadowban depends mostly on how strictly the term is defined. The underlying mechanism it describes is something platforms have acknowledged happens in some form.
A sudden, unexplained reach drop has many other possible causes
Before assuming a shadowban, it is worth ruling out more common explanations first: a genuine change in content quality or format, a broader algorithm update affecting many accounts at once, or simple natural variance in performance. A true, targeted suppression is a real possibility but usually not the most likely one behind a single bad week.