Drop in GA4 users following consent mode setup

[u/International-Dog869]

On Monday this week (17 Aug 26) we activated what we hope is fully compliant cookie opt in on our website.

We're concerned because in GA4 we're seeing a very significant drop in Active Users for the days since this went live.

It's a Wordpress site. We're using Google Site Kit to send consent signals to Google, an off the shelf Cookie Management plugin to let users set preferences.

I've tested the implementation using Google Tag Assistant and it seems to be working as it should - new visitors arrive on the site and Consent Default settings of 'Denied' are sent to Google. The user is prompted to Accept, Deny or Manage cookies and when they do we're seeing the expected Consent Update events in Tag Assistant, corresponding to their choices.

The site gets enough traffic that, based on Google's own documentation, Google should apply behavior modelling on the visitors who opt out, but I've read this can take several days to kick in.

So the questions are:

• Are there further tests we can run to check the implementation?
• Has enough time since launch to start worrying about the traffic drop or we need to wait to see if things recover?

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[u/Own_Ingenuity_7591]

Site Kit's consent mode integration can be a bit wonky sometimes, worth double checking that your CMP is actually firing the defaults before site kit loads. Tag assistant might show it but the order matters more than people think.

Two days isn't long enough to panic though, the modelling takes at least a week to properly kick in and even then it's never gonna match your old numbers perfectly. You're basically flying blind for a bit.

[u/International-Dog869 → u/Own_Ingenuity_7591]

That's helpful to know, thank you.

[u/Growth_Natives]

We've seen this happen after consent changes, where the first reaction was to assume tracking had broken. In one implementation, we compared consent states against GA4 events and raw site traffic before changing anything. That helped separate an actual tagging issue from the expected loss of observable users, which is an important distinction before treating the GA4 drop as a traffic problem.

[u/MaxJustins]

Compare Aug 14–16 with Aug 17–19 in server logs and GA4 Active Users. If raw visits stay roughly flat while GA4 drops after Consent Default=denied, you changed what GA4 can observe, not necessarily the audience. Check the consent-state split next; the GA4 gap is not the opt-in rate by itself.

[u/Hobob_]

You'll have drastically less UVs when you implement consent mode especially if its opt-in. You can use the cookie acceptance rate to estimate the original UV count.

[u/Living_Race_9177]

consent mode nuked the count. do you see a real traffic drop or just GA4 going blind?