Reproduction steps:
1. Open the attached "Stripped" project.
2. Go to "Tools > Build Tests" in the menu bar.
3. Open and run the "mono2x mrelease" build in the "projects" folder.
4. Click "Force GC".
5. Check the information on a device screen.
- Used memory shows ~96 MB.
6. Open and run the "il2cpp mrelease" build in the "projects" folder.
7. Click "Force GC".
- Used memory shows ~128 MB.

Reproduced with:
IL2CPP
iPad Pro 9.7" 10.2.1
5.4.0f3, 2017.01.0b8

Not reproducible with:
Mono

Notes:
- Using Development L2CPP iOS build sometimes shows ~96mb.
- Doesn't reproduce with Android for the user.
- May not be related to iOS only, reproduced with Android (Xiaomi MI NOTE Pro, OS:7.0, CPU:arm64-v8a, GPU:Adreno (TM) 430, Build:Xiaomi/leo/leo:7.0/NRD90M/7.4.27:user/release-keys).

Resolution:
We should depend on platform specific memory profiling tools instead these API methods in .NET.