Custom Themes are no longer shown as Site Templates in DXP 7.4

Issue

In Liferay DXP 7.3, custom themes were seen under Site Templates Pop Up (Control Panel > Site > Choosing the template).
However, in Liferay DXP 7.4, custom themes do not come under Site Templates, and is rather inconvenient to pick a theme.

It is the expected behavior of the Product (Liferay DXP 7.4).
The reason behind this is that the part of the code that was responsible for generating these site templates was the 'Resources Importer', a tool that existed for a very long time and was tied to themes.
The “Resources Importer” gave the possibility of initializing a site with data when a theme is applied to a site and for this, the custom themes were coming under the site templates section.
However, this tool (Resource Importer) has been deprecated from the latest versions, and 'Site Initializers' came into the picture with the same intention. As a result, custom themes are no longer shown as Site Templates in Liferay DXP 7.4 and Site Initializers are present there.

Please note that the Site Initializers is an interface that allows developers to write any desired code that is executed when a site is created and the administrator selects that site initializer. They are presented to the administrator just like Site Templates are, but it's a programmer who decides what the newly created site will be created like. The article Introducing Site Initializers shared earlier explains more about it.