DefaultBloomKernel.uexp (32MB) included on mobile since it is an EngineMaterial referenced.
A PakBlacklist-Shipping.txt (for shipping) and/or PakBlacklist-Development (for development) can be placed in the project's Build/Android and Build/IOS directories to filter out the file from pak files generated:
But it would be better if this wasn't necessary.
1) Create project
2) Package for Android or iOS
3) Look in project's Saved/StagedBuiilds/Android_ASTC/Engine/Content/EngineMaterials for DefaultBloomKernel.uexp (for Package Android ASTC, for example)
This file is not needed for mobile; we will never use FFT bloom.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-45548 in the post.