Steps to reproduce:
1. Create new project
2. Set camera Clear flags to Solid Color.
3. Set Graphics API to Vulkan
4. Build and run on android
5. On device click recent apps button and return to unity build quickly. The colors will be brighter every time

Expected: Color shouldn't be changed when coming in and out of the app
Actual: If you do it quickly, the colors will ramp up with each exit and return. If you click recent apps and wait a second, the colors return to normal

Devices Under Test:
Reproduced on:
Samsung SM G960F, OS:8.0.0, CPU:arm64-v8a, GPU:Mali-G72, Build:samsung/starltexx/starlte:8.0.0/R16NW/G960FXXU1ARCC:user/release-keys
Samsung SM G965U1, OS:8.0.0, CPU:arm64-v8a, GPU:Adreno (TM) 630, Build:samsung/star2qlteue/star2qlteue:8.0.0/R16NW/G965U1UEU1ARB7:user/release-keys
Google Pixel 2 XL, OS:8.1.0, CPU:arm64-v8a, GPU:Adreno (TM) 540, Build:google/taimen/taimen:8.1.0/OPM1.171019.011/4448085:user/release-keys
Google Nexus 6P, OS:8.0.0, CPU:arm64-v8a, GPU:Adreno (TM) 430, Build:google/angler/angler:8.0.0/OPR6.170623.019/4299446:user/release-keys
Samsung SM G950F, OS:8.0.0, CPU:arm64-v8a, GPU:Mali-G71, Build:samsung/dreamltexx/dreamlte:8.0.0/R16NW/G950FXXU1CRC7:user/release-keys

Not Reproduced on:
Samsung SM N950U1, OS:7.1.1, CPU:arm64-v8a, GPU:Adreno (TM) 540, Build:samsung/greatqlteue/greatqlteue:7.1.1/NMF26X/N950U1UEU3BRA5:user/release-keys
Samsung SM N950F*, OS:7.1.1, CPU:arm64-v8a, GPU:Mali-G71, Build:samsung/greatltexx/greatlte:7.1.1/NMF26X/N950FXXU3BRA8:user/release-keys

Reproduced on Unity versions:
2018.3.0a1 (trunk), 2018.2.0b4, 2018.1.0f2, 2017.4.3f1