Duration/Session decrease a half after update app. Don't know why.

Monetizing, Advertising & Marketing Advertising Networks
1

After i update my app on Play Store . The analytics infomation in Google Analytics show me that duration/session decrease a half and revenue is decrease too. :frowning:
User reported some error, i already fix all and update but no thing change.

Before update: Duration/Session: 3min30sec -> 4min30sec
After update: Duration/Session: 1min30sec -> 2min00sec

Anyone know this problem? Thank you!

P/S: Sorry about ENGLISH.