Thanks for bringing this to our attention, I have since entered UE-35333 for this issue. I tested HTML5 packaging alongside Windows, iOS and Android. I did not notice such an increase in size as I did with HTML5.
However as some guidelines, we suggest moving any non-utilized files from your project prior to packaging. Make sure that the textures you’re using aren’t taking up too much memory either.
HTML5 isn’t necessarily a mobile platform however it is more closely related to mobile than to an OS therefore, we suggest using the ‘[Reducing APK Package Size][1]’ for some tips.
I’d also suggest looking at this link for [Reducing Your Package Size][2].
Thanks!
Optimization Guides for Android in Unreal Engine | Unreal Engine 5.1 Documentation
[2]: Testing and Optimizing Your Content | Unreal Engine 5.1 Documentation