How to reproduce:
1. Open the attached '1277219.zip' project
2. Switch Platform to iOS and enable Development Build in Build Settings
3. Build for iOS and open the Xcode project
4. Go to Product > Scheme > Edit Scheme
5. Set Metal API Validation to Enabled
6. Set GPU Frame Capture to Metal
7. Deploy project to an iOS device
8. Click the camera button in Xcode's debug bar
9. Select Memory tab in the Sidebar
10. Observe heap allocated size

Expected result: Heap size is about 10-15MB
Actual result: Heap size is about 30-50MB or more

Reproducible with: 2019.3.0a1, 2019.4.11f1, 2020.1.6f1, 2020.2.0b4
Could not test with 2018.4, because of errors in Unity (multiple precompiled assemblies with the same name)

Reproducible with:
iPhone X (iOS 13)
iPhone Xs (iOS 13)
VLNQA00310 iPad Pro 12.9 1st gen (iOS 13.4.1) (Heapsize: 32-40MB)

Not reproducible with:
iPhone 6S (13.3.1)( Heapsize: 8-10MB)
iPhone XR (iOS 13.4.1) (Heapsize: 7.3-9MB)
iPad 9.7’ 6th gen (iOS 14.2) (Heapsize: 14-16MB)
iPhone SE 2nd gen (iOS 13.6, Unity 2020.2.0b4) (Heapsize: 4-5 MB)

Notes:
- Seems to be reproducible on iPhone X and similar devices according to users' reports
- Screenshots of the memory usage are added to the Edit