From what I can tell, if you close the app while a short is playing, you’ll be dumped back into shorts when opening the app again. I’ve made it a point to always go back to the home tab before closing the app, which seems to avoid the issue.
I assume their goal is to make YouTube feel like TikTok, for those who want that.
Personally, I think there should be a setting so I can pick which page the app opens up to. I’d like it to open up to my Watch Later list, or subscriptions.