Wasabi charges a fee based on the amount of gb that is deleted per month under that 90 days. Their wording is confusing as all can be but it’ll cost you more than 5.99 + Sales Tax per month if you delete files earlier than 90 days.
Here’s an easier explanation: Wasabi Storage Review: How Good is this Object Storage Provider?
Still based on this they don’t have a real time calculator to see at the end of each day (with projections into the next 90 days) what the current running cost will be or an approximation is. You just get a surprise bill at the end of the month. They tell you how to calculate it but are you really going to sit there and manually calculate it based on every single file you deleted?