Hello,
I’m working on SPA website with main domain and subdomain for each product on it. I have implemented web and server tracking by GTM using Stape.io and using custom loader with enhanced ad blocker, cookies keeper and user identifier depend on Stape user ID and adding this to domain and all subdomains, and tracked pageview with trigger of history change of pushstate only to avoid duplication.
But I met abnormal issue, we launched campaigns in social media with utm parameters, they appeared on Traffic report on GA4 as sessions with small number of events fired when they choose product and navigate to subdomain and on Mixpanel I found only pageview of the landed page from ads on the users activities and then session broken and looked on clarity I saw sessions of them are in seconds, while users came from google/cpc are tracked well.
Notice: I already make cookies domain auto on google configuration tag and mixpanel initialization and type the domain on unwanted list of referral.
Notice 2: I have tested it on GTM Preview mode for web and server and it worked well.