Element subtree: an element inserted 2 s after load. EasyList ###AdSkyscraper (un-hideable tier). The banner is plain text with no resources, so Brave's subtree rule calls it first-party. Brave's MutationObserver queries new ids (content_cosmetic.ts:262-339), hides the match and, in Standard, its un-hide pump may then un-hide it.
Hypothesis: Standard hidden, then visible; Aggressive hidden. This is the cell the measurement is least sure of: a selector the pump has already exhausted is not re-evaluated (content_cosmetic.ts:702-710).
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.