OneTrust is a privacy management software that helps organizations comply with privacy laws and regulations. Here's how it works:
When a customer visits the website, OneTrust triggers a pop-up asking for cookie consent. Based on the customer's response, OneTrust informs Google Tag Manager of the availability of cookie usage.
If customers visiting OBS do not consent to OneTrust, data collection will be restricted. As a result, in countries where OneTrust has been implemented, there will be differences in metrics such as traffic compared to before its implementation.
Reference
GA4 & Consent Mode - GP One Project