Average engagement time per session different in GA4 and BigQuery for screens

Here is my code to calculate monthly "average engagement time per session" for screens in BigQuery:

select DATE_TRUNC(EXTRACT(DATE from TIMESTAMP_MICROS(event_timestamp)), month) as trunc_month, params1.value.string_value AS screen_name, avg(params2.value.int_value/60000) as avg_engagement_time_min, FROM `table_name` as base, unnest(event_params) as params1 , unnest(event_params) as params2 where event_name = 'user_engagement' and params1.key='firebase_screen' and params2.key='engagement_time_msec' AND FORMAT_TIMESTAMP('%Y%m%d', DATE_TRUNC(TIMESTAMP_MICROS(event_timestamp), month)) BETWEEN @DS_START_DATE AND @DS_END_DATE group by 1,2 order by 1,avg_engagement_time_min desc

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The resulting figures are quite different from GA4 results. For example, for a particular screen in November, GA4 is showing 49 seconds as the "Average engagement time per session" when I select a date range of 1 Nov to 30th Nov, and bigquery is showing 4.73 minutes for November.