I know nothing of Snowflake pricing, but how big is their infrastructure that leaving it on for an extended amount of time could see that much savings?
To put it another way, to rack up $500k spend for 30 days of constant provisioned time:
$500k/(30*24) = $694/hour
Presumably, with the 10 minute blocks, there was idle time where the spend was zero, so the instantaneous amount would be higher.