TEXTURE has wrong size in memory

Please help me, my texture is 16000 KB. In unity is ETC2 is 4 MB, but when I profile the memory, is even more than original size, it shows 20 MB !
Is it a bug ?

Apparently ALL MY TEXTURES are compiled into an RGBA8 !! which increases the size!

It looks similar to this bug:

Please help! I am in Unity 2017 lts last update