FSE: Previewing in a new tab should reflect template changes even before saving

[edequalsawesome]

Description

On a published post or page, if

• you change the Template in the Page/Post editor right-side panel and click Preview in new tab

or

• you change the Template in the Page/Post editor right-side panel, and then click Edit to end up in the Template Editor, and lastly click Preview in new tab

the change is not reflected.

It only reflects if you preview after you save changes by clicking Update

Step-by-step reproduction instructions

1. Open a published page from the Pages > All Pages area of WP Admin
2. Change the template used for the page from the Templates panel of the sidebar
3. Click Preview > Preview in New Tab

Screenshots, screen recording, code snippet

Preview.Changes.mov

Environment info

Gutenberg 12.6.1
WordPress 5.9.1

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes

[annezazu]

Thanks for reporting this. I see this as a duplicate of the following issue: #28208

I'm going to close this out as a result but, if I'm missing something, please let me know!