Yeah it’s a bit complex because unreal is a bit complex. It has 2 rendering pipelines and also within those pipelines additional shaders for instanced stereo and mobile multi-view which sometimes get jumbled up with the local path (android preview mode) which is yet another emulated shader path.
You now have Virtual Shadow Maps in Deferred as well as “Shadow Maps” or Cascade shadow maps (which nobody really test because VSM is now default) and also forward rendering isn’t used for anything other than mobile and VR (Quest) development so even there it just usually gets stomped over by shader code that works against deferred rendering.
If the bugs weren’t present then you also have to deal with configuration and device profiler.
The shadow issues your seeing could be due to android scalability settings as well as profile issues for the Quest 2/3 which I’ve tried to outline here.
I’m sorry your going through this but I hope you’ll manage to overcome them 