Email template updating does not function as expected

Describe the issue: When attempting to update the content of email templates, including the subject, body, and footer, the update payload is not being generated correctly based on the provided inputs. The body section is updating intermittently, but the subject field remains unchanged in every update call. However, the changes to the footer input are being applied correctly. Please refer to the attached request image for details.

How to reproduce:

Navigate to the Email Templates item in the Branding section.
Access the content tab and make edits to the subject, body, and footer fields.
Click the Save button.

Expected behavior: Email templates should be correctly updated according to the input changes.

Environment information (Please complete the following information; remove any unnecessary fields) :

Product Version: [e.g., IS 5.10.0, IS 5.9.0]
OS: [e.g., Windows, Linux, Mac]
Database: [e.g., MySQL, H2]
Userstore: [e.g., LDAP, JDBC]

wso2 / product-is

Email template updating does not function as expected #18957