Determine which template-{slug}.php is being loaded

I am trying to make a personal plugin that does specific things based on what is loaded. In this example, in my action method I want to perform one function if the currently loading page is using the template-blog.php template, if it’s a single blog post (loading single.php do a second function, anything else do a 3rd function

remove other tabs in new wordpress media gallery

I recently updated my WordPress site into the latest WordPress version, and i added a code to my functions.php that would add a capability to subscriber to upload using WordPress media upload. I successfully remove the media library tabs on the later version of WordPress but when I updated the version it seems like the code does not work anymore. Any ideas how to fix this?