Custom Page Template for Package

I created a custom page template inside a package in my project. The template file is inside “packages/my_package/page_templates” folder in the package and the page type and template are installed using CIF. Everything installs fine but when I create the new page with the template, the page is wrapped by the subpage template of my project (inside application/theme/my_project/subpage.php) . How do I make it so that this custom page template isn’t wrapped inside the subpage

Could you provide a minimal reproducable example (MRE)? I can’t really imagine what’s going on based on the description.