Optimization of requests in BigQuery

I am attaching a request
WITH Query AS (SELECT
CAST(FORMAT_DATE('%Y-%m-%d', PARSE_DATE('%Y%m%d', event_date)) AS Date) AS date,
CAST(FORMAT_TIME('%T', TIME(TIMESTAMP_MICROS(event_timestamp))) as Time) as time,
event_name,
geo.city city,
platform,
CASE
WHEN K.value.string_value IS NULL THEN CAST(K.value.int_value AS string)
ELSE
K.value.string_value
END
AS UserID
FROM
\chasto-prod.analytics_324473216.events_20221212`, UNNEST(event_params) AS K WHERE K.key='user_id' order by date desc) SELECT count (*) EventCount, event_name, date, city, UserID, platform FROM Query WHERE date > PARSE_DATE('%Y%m%d', u/DS_START_DATE) AND date < PARSE_DATE('%Y%m%d', u/DS_END_DATE) group by event_name, date, city, UserID, platform LIMIT 1`

/r/GoogleDataStudio Thread