Question
A seller's listing rockets up your marketplace ranking after a wave of 5-star reviews. Each review is individually plausible (different accounts, varied text, real-looking purchase history) and none trips your spam-text filter. But trust & safety suspects a paid review ring. The accounts reviewing this seller also co-review a small cluster of other sellers, were created in batches, and share subtle linkage (similar email patterns, overlapping IPs at signup, reviews posted in tight time windows). Volume is low — only ~300 reviews — so no rate alarm fired. How do you triage, confirm manipulation, contain it fairly, and harden ranking against it?
Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.