Why is the Solo topology estimate higher than production?

Hi guys, I just added datomic cloud in aws marketplace, and am in the process of configuring it.
But it’s a little confusing to me that the estimate calculation is higher for the Solo topology than for the production.
Solo: $25/month
Production: $18/month
Also the instances are different between the “Whats in this version” section and the “Infrastructure Pricing” section.

For Solo:
Whats in this version:
t3.nano for Bastion
i3.large for Datomic
Infrastructure pricing:

For Production:
Whats in this version:
t3.nano for Bastion
t3.small for Datomic
Infrastructure pricing:

Here are the screenshots:


Datomic Solo is only for an older version of Datomic Cloud (781-9041 and earlier).

The latest version of Datomic Cloud allows for lower costs with t3.smalls on a Production stack. If you’re not upgrading an existing system then we recommend that you use the latest Production fulfillment option.

Understood, thank you.