<b>Q: Why does my GA4 session count change depending on which report I open?</b>

<b>Q: Why does my GA4 session count change depending on which report I open?</b>

A: Almost always reporting identity, sampling, or the (not set) bucket — not a tracking bug.
— Standard reports use a different aggregation than Explorations, so Explore can apply sampling on large date ranges. Look for the orange triangle top-left of the Exploration; hover it to see the sampling percentage.
— Explorations also respect your reporting identity (<code>Admin → Data display → Reporting identity</code>); Blended vs Observed shifts user and session math.
— Thresholding hides small rows when Google Signals is on, lowering visible totals.

Narrow the date range or switch to Observed identity and the numbers converge.

TL;DR: Sampling + reporting identity + thresholding, not lost sessions.

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