Seestar App has two types of albums:
Saved Album (Local Storage)
Photos in this album are stored directly in your phone's storage (under DCIM/com.zwo.seestar/).
If you switch to a new phone, the images from your old phone won't automatically appear on the new one. You need to manually transfer them.
Seestar Album (Device Storage)
Photos in this album are stored inside the Seestar S50 device itself.
These images remain accessible no matter which phone you connect to Seestar.
Since you changed devices, the images in the Seestar Album remain unchanged, but the ones in the Saved Album are still on your old phone.