Google Photos Deletes My Gallery and Wastes My Phone Storage

I recently switched from iOS to Android and transferred all my old photos to my new phone. I now truly regret doing that. I received a notification saying I won’t be receiving emails after the 27th, and I have no idea what will happen to my photos after that. Out of panic, I subscribed to Google Photos, but I still don’t understand how this system works.

My new phone has 512 GB of internal storage, yet the 15 GB I'm using isn’t enough? Why am I being forced to pay for storage when I have plenty of free space on my device? Even worse, when I delete something from Google Photos, it disappears from my gallery too. Isn’t this supposed to be a backup service? Why are the cloud and phone storage so deeply linked that I lose everything on my phone when I remove items from Google Photos?

I tried to restrict Google Photos' access, but I’m still warned that my entire gallery will be wiped if the Google Photos backup is cleared. What kind of ridiculous system is this? I bought a high-capacity phone so I could store everything locally—but now I can’t even use that space the way I want. Fix this sync nightmare, Google. You're causing users unnecessary stress and confusion.