To clarify the priority matrix/ preference of transactions flow based on the above two factors.
Transactions picking a gateway based on your preferred currency instead of the set smart routing rule.
Explanation for this behavior:
Chargebee’s hierarchy is Customer >> Subscriptions >> Invoices / Transactions etc.
Hence when your preferred currency is set by using either API or
Chargebee’s admin console, it indicates that you wish to override the base currency/selling currency and be charged in their preferred currency or local currency (mostly).
This preference overrides the smart routing configuration and forces the transaction through the gateway which is set for the preferred currency on the merchant’s site.
The above option can be accessed via the Chargebee admin console under the edit customer option.