Discrepancy in Google Analytics 4 data in Looker Studio between GA connector and BiqQuery connector

[900rr]

Since Google imposed disastrous API quotas and made any serious reporting impossible, I am forced to look into alternative ways to present the data.

So, I have a Google Analytics 4 property synced to BigQuery and connected to Looker Data Studio via the BigQuery connector (a), as well as the same Google Analytics 4 property connected via the Google Analytics connector (b)

The number of events is identical in both data sources. When I enter this query into Google BigQuery, The session count is 117,379 (a), but Google Analytics 4 connected via GA Looker connector displays 183,363 (b). Why do I notice the discrepancy? The observed date is the same for both (last month ) and no filters are applied.

This query is from google doc. https://developers.google.com/analytics/blog/2022/hll#sessions

SELECT  
  HLL_COUNT.EXTRACT(
    HLL_COUNT.INIT(
      CONCAT(
        user_pseudo_id,
        (SELECT `value` FROM UNNEST(event_params) WHERE key = 'ga_session_id' LIMIT 1).int_value),
      12)) AS session_count,

FROM `bigquery-GA4mydata.events_202301*`