So this update was necessary. Apple re-released iOS 13 Developer Beta 3 after a week of the First release if Beta 3. This update is now also available for the iPhone 7 and the iPhone 7 plus users. The update came at around 100-150 Megabytes depending on which device you are using and which firmware you are updating from. Apple re-released Beta 3 because it had a ton of bugs which made the device unusable.
Some of the common bugs in the first release of Beta 3 are:
1. When you press on the volume keys, it triggers silent mode.
2. Control Centre does not work properly.
3. The iPhone would freeze often.
4. Rotation would not function properly
5. LTE and WiFi issues during a FaceTime Call.
6. When you press the volume buttons to take a picture in the camera App, the Camera interface is blurred.
So Apple had to fix a few of the above major bugs and re-release Beta 3.