Cell F5 (N6, N29): a shipped generic $removeparam=gclid in a default-engine list (uBlock Origin Privacy; Brave Default Privacy Filters). Graded through /echo, which returns the URL the upstream received.
Expected in Brave: first-party gclid kept in both modes, because Brave always discards the default engine's removeparam and its query filter exempts same-site requests. Third-party rewritten to /echo?keep=1 in both modes: Brave's query filter strips gclid from cross-site GET requests. Ours applies $removeparam from any list, so it rewrites both: the first-party row is the written difference. The control without gclid is unchanged on both.
Rows, rules and Brave's verdicts are in pages/network-fixtures.json (ENG-2592); until the nightly Brave arm measures them they are hypotheses. The runner grades from CDP, never from this page.