Hello,
I know that Piwik is not responsible for GA4 
but, I’m a little bit stuck at the moment, and I’m wondering if I’m alone in this situation.
I implemented the GA4 gtag code with user_id parameters through Piwik TMS.
The data I collect in GA4 are not fully accurate: huge amount of user, the link between Google Ads & GA4 seems to not work…
The Google support asked me to implement a new GA4 code without modification (no user_id…) The data are similar, but the link with Google Ads works…
For them:
Yes, we were really trying to research and understand a lot of things in your account. However, the only issue that we could find here is the way you implemented the codes and Third Party Tag Manager which you’re using as the GA4 and UA are working completely fine for other users.
You can either get in touch with the Provider of the Tag Manager System or try to use the google tag manager provided by Google itself.
So I have two questions 
- Is someone already had the same issue and found a solution?
- How to condition the triggering of a GTM container on the Piwik CMP?
Many thanks,
Hi ValPiwik!
Could you please elaborate on what you mean by the link between Google Ads & GA4 seems to not work? Do you mean Google Ads conversions?
In general, if you’d like to add the GTM container via the Piwik PRO Tag Manager (and therefore have the ability to use our Consent Manager) you should probably use a cutom HTML tag with a specific consent type attached to it.
it shouldn’t be piwik related but I might be able to help you - did you link GA4 and Google Ads in settings? Both from GAds and GA4 settings menu there should be way to select account you want to link data between.
I assume you are using Piwik TMS + GA4 for free consent service 
Hello @anthonybartczak, @Jakub_Fidala,
In GA4 admin panel, we can link Google Ads: so we import Google Ads data into GA4.
But in GA4, when I analyze the data, the volume of sessions attributed to Google Ads is not accurate…
The official answer from Google is that the issue come from Piwik TMS…
It is a funny answer because I use also Piwik Analytics and the data is accurate for Google Ads^^
My conviction is that GA4 doesn’t work very well if we use the gtag code, especially if we want to use some advances functions like the user_id tracking…
So, I think that using GTM only for GA4 could fix my issues.
But, I don’t like the idea to implement a container (GTM) into another container (Piwik)… I have some concerns regarding the impact on my website (speed).
I use Piwik TMS and Piwik Analytics for a part of my website.
But, I don’t have the budget for the paid license of Piwik to deploy it on all my website… It is why I also use in parallel GA4…
Are you using some UTM tagging in Google Ads or just built-in gclid? Because gclid should match almost 100% of data in GA4 between clicks and sessions
Just the gclid
I recreated a code to implement to check if it is a bug…