Execute Stored Procedure - Inconsistencies with function/Smart Service across architectures

We are using the “Execute Stored Procedure” plugin and have noticed differences across architectures.  On a SAIL interface, we are using the fn!executestoredprocedure function, and the stored procedure we are calling defines and executes 2 prepared statements, both of which select data. 

In our environment with Appian 20.3, we are receiving the following error when executing the function: “Use the Execute Stored Procedure Smart Service to modify data. This function must only be used to query data, not modify”.  However, we are not modifying data via the stored procedure, and furthermore, when we call the stored procedure in the Execute Stored Procedure smart service, it works fine.  Also, when we execute the stored procedure directly in the DB via PhpMyAdmin, it works fine.

The environment where we are receiving this error is Appian 20.3 on cloud with MariaDB 10.5.6

However, when we do the same thing on another Appian 20.3 cloud environment with MySql 5.7, it works fine from the fn! call. 

So, our questions are:

1. Why can we execute the stored procedure fine via the smart service, but not the function?
2. Why does the function error on a MariaDB environment, but work in a MySql environment?