You have to wrap inside of a server action and then you can call the server action with that login to the client action.
Instead of doing this

You wrap inside of a server action

And then you call the server action

If you don't know how to create server actions, you just need to go to the logic tab and right-click on the server action folder and "Add Server Action", don't forget the inputs or outputs that you will need to pass from or to the client action where you are going to call the server action.

There are already some posts about this if you search for the error in the forums,
I found some:
https://www.outsystems.com/forums/discussion/62194/security-warning-youre-exposing-a-database-operation-in-the-client-side-validat/
https://www.outsystems.com/forums/discussion/58717/validate-the-data-in-a-server-action-before-changing-the-database/
And I found also a OutSystems post about warnings
https://success.outsystems.com/Documentation/11/Reference/Errors_and_Warnings/Warnings/Security_Warning?_gl=1*kj7u44*_ga*MTc5Nzg1NzgxOS4xNjUyNzQ4Mjk4*_ga_ZD4DTMHWR2*MTY1NDE4OTIyMi4xMjguMS4xNjU0MTkyNzcwLjYw
Regards,
Márcio