iOS app size is huge on devices while .ipa size is normal

There's a plenty of similar questions, however, my case is different: I make a release build in Unity editor, platform is universal in player settings, then I archive my game in xCode 7.3.1, resulting archive size is 1.89 Gb. Then I export archive to .ipa without bitcode and app symbols for App Store deployment. The resulting .ipa size is 60 Mb, which is great. However, when I then upload it to iTunes connect and install it on any device via Testflight, the size on my device is 1.2 Gb. The same is with bitcode included. I got the same huge size after compiling the game to my devices via xCode.

Unity 5.3.4f1 personal