Update time: May 30, 2026
Issue Overview
Starting from mid-May 2024, some Google Analytics 4 properties experienced a severe and unexpected drop in New Users data, in some cases declining by more than 90%.
In affected accounts, reports showed:
Root Cause Analysis
1. Inconsistent Data Recovery Across Properties (Possible GA4 Bug)
One key observation is that:Some GA4 properties started recovering data around June without any configuration changes，Other properties continued to show missing or severely reduced New Users data
This inconsistency strongly suggests a platform-side issue or delayed backend processing bug within GA4 rather than a user implementation error.
In other words, the behavior is not reproducible through configuration changes alone, making it difficult to diagnose purely from the client side.
2. Invalid or Corrupted User ID in User Explorer
Please check whether the Effective User ID appears abnormal, such as:
If this issue is present, it is often related to enabling User-Provided Data Collection in GA4.
Due to the page’s code structure, GA4 may automatically capture incorrect values as the User ID.
This is a known GA4 bug.
Read More：「GA Bug」Effective User ID in the Exploration Eeport is Garbled
Solution
If the Effective User ID is garbled, please turn off the User-provided data collection.
Others, waiting for official fix.