This is a breaking change release (as 4.0.0 was, but it was unpublished as a serious bug was found)
Please read the migration guide: https://github.com/react-native-community/react-native-device-info/wiki/V3-to-V4-Migration-Guide
It is released with no changes from 4.0.1-rc.1, previous releases and the CHANGELOG have notes of the details from 3.x to 4.x