I must admit that I had not heard of this problem before. Perhaps some backlogged files from the previous version are causing this problem. 🤔
In this case, you can try to 'wipe cache partition' through the Recovery mode:
- Turn off your device
- Connect your device to the PC via USB (not to the charger)
- Wait until the message that the device is being charged appears
- Press and hold down the volume up and then power buttons and hold them until the device turns on
- Recovery menu should appear
- from there select "Wipe cache partition" (you can navigate using volume up/down buttons and confirm with a power button).