Group by day and group by hour gives different results for the same day

Grafana InfluxDB
1

Hi
I have a query, and when I group it by day it gives a different result as when I group it by hour.
This is the green one

SELECT non_negative_difference(last("value")) FROM "steps" WHERE ("entity_id" = 'oneplus_a6003_steps_sensor') AND $timeFilter GROUP BY time(1h) fill(previous)

and the orange one

SELECT non_negative_difference(last("value")) FROM "steps" WHERE ("entity_id" = 'oneplus_a6003_steps_sensor') AND $timeFilter GROUP BY time(1d) fill(previous)

How can I adjust the query so both will give the same results?

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