Reproduction steps:
1. Open the attached user's project "Il2cppproj.zip"
2. Go to Project settings > Player > Other settings and select IL2CPP Scripting Backend
3. Go to Build Settings
4. In the IL2CPP Code Generation section select Faster (smaller) builds option
5. Build and run the application on the Android device
6. Open the Android Logcat window and observe

Expected result: Box integer is equal to itself
Actual result: Box integer is not equal to itself

Reproducible with: 2021.2.0b12, 2022.1.0a10
Could not test with: 2019.4.31f1, 2020.3.20f1, 2021.1.22f1 ("Faster (smaller) builds" available in alpha builds only from 2021.2.0a17 onward)

Reproduces with these devices:
VLNQA00277 - Asus ROG Phone (ASUS_Z01QD), OS: 8.1.0, CPU: Snapdragon 845 SDM845, GPU: Adreno 630
VLNQA00121 - Samsung Galaxy S9 (SM-G960F), OS: 9.0.0, CPU: Exynos 9 Series 9810, GPU: Mali-G72
VLNQA00006 - Samsung Galaxy S7 (SM-G930F), OS: 8.0.0, CPU: Exynos 8 Octa (8890), GPU: Mali-T880
VLNQA00034 - Google Nexus 4 (mako), OS: 5.1.1, CPU: Snapdragon S4 Pro APQ8064, GPU: Adreno 320
VLNQA00070 - LENOVO PHAB2 Pro (Lenovo PB2-690M), OS: 6.0.1, CPU: Snapdragon 617 MSM8952, GPU: Adreno 510

Not reproducible with these devices:
VLNQA00109 - Xiaomi Mi Note Pro (MI NOTE Pro), OS: 7.0.0, CPU: Snapdragon 810 MSM8994, GPU: Adreno 430

Notes:
- Not reproducible when Mono Scripting Backend is selected