I made a test project to see the amount of physics objects my phone can handle.
After testing it on my device, I tested it on another and noticed that the shadows between both of them are drastically different.
In project settings the shadows resolution for mobile is 2048 and force vertex shading is turned off.
This is on my phone, which uses a Helio A22 with a powerVR GE8320 GPU

And this is on the other phone, which uses a Snapdragon 439 with an Adreno 505 GPU

Why is there such a considerable difference in the shadows?