Element subtree: an element inside a cross-origin frame. The frame is served from other.test-adblock.com (a different origin, the same site) and holds a plain-text ###navAdBanner match (EasyList, un-hideable tier). Brave gives a frame that is cross-origin to the top frame the Aggressive policy, with no un-hide (cosmetic_filters_js_handler.cc:636-643); whether it means origin or site is what this page measures.
The frame reads its own banner and posts the read to this page (frame_reports). Hypothesis in both modes: hidden, and still hidden on the settled read; Standard hidden-then-visible would mean Brave keys the policy on site, not origin.
Expectations are Brave's verdicts, stated in pages/cosmetic-fixtures.json (ENG-2306); until Brave is measured they are hypotheses. The status line mirrors the Standard expectation.