What are the four reasons the numbers fell?
| Cause | What it does | Who it affects |
|---|---|---|
| Apple's App Tracking Transparency (2021) | Asks iPhone users whether an app may track them across other apps and websites. Most say no, so Meta's app cannot connect the ad to the purchase | Every advertiser whose customers use iPhones, which in Australia is more than half |
| Browser limits on cookies | Safari and Firefox shorten or block the cookies that tie a visit to an earlier click. Safari caps a tracking cookie set by script at seven days | Longer buying cycles, where the sale comes weeks after the click |
| Ad blockers | Remove the Pixel and the Google tag before they run, so the visit is never measured at all | Younger and more technical audiences most |
| Consent banners and consent mode | Where a banner is required, visitors who decline are measured only in aggregate; consent mode lets Google model the missing conversions from the ones it can see | Businesses with visitors in the EU and UK |
None of these touch the sale. A customer who declined tracking still bought the thing. What they touch is the platform's ability to say which ad deserves the credit, and the number in Ads Manager or Google Ads goes down while the number in the shop stays put.
What does consent mode actually do?
Google's tags (the Google tag for Analytics and Ads, and Tag Manager) check a consent signal before they store or read a cookie. With consent, they measure normally. Without it, in Google's words (Google Ads Help, "About consent mode"), the tags send cookieless pings that carry no personal identifier, and Google uses the pattern of consented visitors to model how many of the unconsented ones converted. Since March 2024, Google requires consent mode version 2 for anyone running personalised ads to people in the European Economic Area and the UK. For a business with Australian customers only, it is optional, and the banner that drives it is optional too.
What does the gap look like in one business? (example figures)
A Cairns dive shop sells tours online and runs Google Ads and Meta at $2,400 a month between them. Its own booking system is the source of truth.
| Month | Bookings in the booking system | Conversions Google Ads and Meta reported together | Share the platforms saw |
|---|---|---|---|
| Early 2021 | 96 | 71 | 74 percent |
| Late 2021, after the iPhone prompt | 101 | 52 | 51 percent |
| 2026, Pixel plus Conversions API, Google enhanced conversions on | 118 | 84 | 71 percent |
The owner nearly cut the Meta budget in late 2021 because its reported bookings halved. The booking system said bookings had grown. Two years later, sending purchase events from the server (the Conversions API) and from Google's enhanced conversions, which match a hashed email to a signed-in Google account, won most of the visibility back. The sales were never missing. The measurement was.
Platform conversions ÷ real sales = how much of your business the platform can see
84 ÷ 118 = 71 percent
What should an Australian owner actually do?
Three things, in order. Compare the platform's conversions with your own sales or bookings every month, so a measurement change never reads as a sales change. Send conversions from your server as well as the browser: the Conversions API for Meta, enhanced conversions for Google Ads, both of which Shopify, WooCommerce and most booking tools switch on with a setting. And write the privacy policy honestly: what you collect, which platforms you share it with, how someone opts out. A banner is a choice for Australian visitors and a requirement for European and British ones, so a shop that ships overseas needs one that works properly, with consent mode behind it.
What does Cora do with consent and cookies?
CoraVision reads the conversions Google Ads and Meta report every night once they are connected, and it reads Google Analytics 4's purchases and key events too, so the gap between what the platforms saw and what the site recorded is visible in the same numbers. Your Trust Score, which rates how far your numbers can be trusted, loses points for a paid channel with no conversion tracking and earns them back when the tracking is repaired. Cora reads the numbers and shows you where the gap is on your own screen; you, or your developer, make the change.
Questions
Do I need a cookie banner in Australia?
Not under Australian law as it stands in 2026. You need a privacy policy that says what you collect and share. A banner is required for visitors in the European Union and the UK, so an Australian shop that sells there needs one for them, and Google requires consent mode for ads personalised to people in those places.
Is a drop in reported conversions a drop in sales?
Check the till before the dashboard. If sales held and the platform's conversions fell, the measurement changed, not the business. Compare the platform's number with your own orders or bookings for the same month.
Will Chrome blocking cookies make this worse?
Chrome did not block third-party cookies in the end: Google dropped that plan in 2024 and 2025. Safari and Firefox already limit them, and iPhone tracking prompts do more damage to ad measurement than any browser setting.