When doing a Release build, the generated .so files are 10 times bigger because they contain debug information. One needs to strip debug info from them manually to have a small library.

Release builds should behave as their name suggest: producing releasable binaries without debug information.

This is the general configuration which comes up in QtAA builds:

   -DCMAKE_CXX_FLAGS=-g -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security  
   -DCMAKE_CXX_FLAGS_DEBUG=-fno-limit-debug-info 
   -DCMAKE_CXX_FLAGS_RELEASE=-O3 -DNDEBUG 
   -DCMAKE_CXX_FLAGS_RELWITHDEBINFO=-O2 -g -DNDEBUG

As it can be seen above, some part of the build system sets the -g flag globally to all build types. This happens by default without any special flags as well.