Recently, I came across an insightful post on Simo Ahava's blog that sheds light on a significant update to Google Tag Manager (GTM) that took effect on April 10th, 2025. While it's now June 28th and this update has been in place for a couple of months, it's still important to understand the changes and their impact on data collection.
If you're using Google Ads or Floodlight tags through GTM, this change may affect how your tags behave — especially if you haven’t explicitly added the Google Tag to your container. The update changes how GTM auto-loads the Google Tag (gtag.js) when certain events are fired.
What exactly changed?
Before April 10th, if a Google Ads or Floodlight tag fired and there was no Google Tag explicitly present in the GTM container, GTM would quietly inject a minimal version of the Google Tag. This was basically a stripped-down version of gtag.js, just enough to let the conversion tag run.
However, starting April 10th, that minimal version is no longer used. Instead, GTM now automatically injects the full Google Tag with all its settings — including:
- Enhanced Conversions (if enabled in your Google Ads account)
- User-Provided Data (UPD)
- Consent settings (if configured)
- Any other configurations associated with that tag ID
This behavior is done automatically at runtime. You won’t see the tag in your GTM container UI, but it will be injected and active behind the scenes if certain criteria are met.
Why does this matter?
This change may seem minor, but it can have real consequences for your tracking and reporting.
1. Your data might look different
Because the full Google Tag now includes more functionality, you might start to see more conversions being reported, or at least different patterns — especially if enhanced conversions or UPD are now firing unexpectedly.
2. You might not be aware that it’s happening
Since the full tag is injected at runtime and doesn’t show up in the container editor, it can be easy to miss. If you’ve relied on the minimal tag before, you might not realize that this behavior has changed — and that your tags are now collecting more data than before.
3. It creates a ‘black box’ effect
You may not know exactly when or how the full tag is being loaded unless you inspect it in the browser. This makes debugging harder, especially if you’re trying to isolate why certain data is appearing in your reports.
Key clarifications from Simo’s post
Simo Ahava pointed out several important details in his original article:
- This update only applies to Ads and Floodlight tags, not GA4.
- The full tag being injected includes all the configuration defined in your Google Ads or Floodlight platform.
- If you've manually turned off Enhanced Conversions or UPD in your Ads interface, those settings will still be respected.
- Server-side GTM is not affected by this update.
- Consent Mode will still work as expected — the auto-injected tag honors your existing Consent Mode setup.
Should you take action?
✅ Yes — if you want more control.
The best practice is still to manually add the Google Tag to your GTM container. This ensures:
- You have full visibility into which tags are firing
- You control when the Google Tag loads (e.g., on pageview vs. custom event)
- You can more easily debug and maintain your setup
If you rely on the auto-loading behavior, things might work — but you’re giving up a lot of transparency and control, which isn’t ideal when managing mission-critical tracking.
My thoughts
I think this update reflects Google's increasing push toward automation and tighter integration between their platforms. In some ways, that’s helpful — especially for marketers who just want to get conversions tracked without worrying about technical setup.
But as someone who prefers clarity and full control in GTM, I would much rather explicitly add all necessary Google Tags. It helps with auditing, debugging, and ensuring no surprises down the road — especially when working in environments with sensitive privacy requirements or legal compliance concerns (like GDPR or CPRA).
Final note
If you received an email from Google about this change but you’re not using Ads or Floodlight tags in your GTM container, you can probably ignore it. It was sent to a broader audience than necessary.
Still, it’s a good reminder to check your GTM setup. Are your tags firing the way you expect them to? Are you relying on automation you weren’t even aware of?
GTM gives us a powerful toolset — but only if we use it intentionally.
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