Two mutation traps observed while executing ad-set pauses and a post-publish enhancement audit in Meta Ads Manager (adsmanager.facebook.com), both verified on fresh document loads:
1. Pausing an ad set can offer to double a sibling's budget. On toggling an ad set Off, Meta sometimes raises a modal: "You can distribute $15.00 of unspent budget from the ad set you just turned off" — pre-targeted at a specific sibling ad set with a concrete proposal (here: N1 $15.00/day → $30.00/day, "+79% Results") and two buttons, Don't update budget / Update budget. An automation that dismisses dialogs by clicking the primary (rightmost) button would silently double a live budget. It does not fire on every pause (2 of 3 pauses in the same session got no dialog). Handle it by matching the exact Don't update budget label, then re-verify every sibling's budget on a fresh load — the budget column read $15.00/day everywhere afterward.
2. Publishing an ad re-enables Website highlights → Contextual links even when the pre-publish audit disabled them. Four ads were built with website highlights explicitly disabled and audited clean before publish. On the first post-review inspection (day 8 of delivery), 2 of 2 checked ads had Website highlights: On with Contextual links: N On — Meta had auto-picked 2-3 links to OTHER pages on the advertiser's domain and was rendering them on the ad, diluting the single-landing-page design of the experiment. The per-ad summary counter is not a reliable tell: one ad showed Creative setup (1/4) and the other Creative setup (0/4) while both had contextual links On inside the dialog; you must open the Creative setup editor and read the Website highlights badge itself.
Fix sequence that persists: open Creative setup → click the Images: N Off/On | Contextual links: N Off/On row to expand → uncheck the Contextual links master checkbox (the badge flips to Off and all tile checkboxes clear) → Save → Publish (goes out as Publishing 1 of 1, touching nothing else) → fresh document load → re-open the dialog and confirm the badge reads Off. Note the master checkbox may not be reachable via [role=checkbox] queries left of the label; clicking the checkbox glyph's screen coordinates (taken from a screenshot of the expanded row) worked when DOM-role scans found nothing.
Operational rule from both: after ANY publish on this platform, re-audit enhancement flags once the ad leaves review, and after ANY pause, re-read sibling budgets. Meta mutates adjacent state on both write paths.