Custom integer lookback windows for click-through and engaged-view conversions

What it breaks

A property that shortens or lengthens a window changes its key-event counts against its own history and against Google Ads' window; comparisons across the change date read as performance moves.

Who it hits: Anyone who changes a window; anyone comparing GA4 key events to Ads conversions.

The fix

Annotate the date, run the old and new window side by side for 28 days in the reconcile sheet, and match the Ads conversion window when you compare the two.