When I restarted my phone after the update, I saw that Initializing Phone was shown in the opening menu and I investigated this situation.
I have the following information.
This is the normal operation concept of your device.
Based on the advanced Google Security Policy of the Android 9.0 (Pie) Operating System, if you set the device's lock screen with Pattern, Pin or Password, the Phone Start screen may appear for a few seconds while the device is booting and you can experience a Black Screen experience of 1-2 seconds before the device switches to the Home Screen. .
Since the FBE (File Based Encryption) enabled during boot is applied to Galaxy Note10 & Galaxy Note10 +, you may feel that Note10 / 10 + takes a longer time to complete the system boot than other devices.
we are sorry for the issue you have been facing.
If system boot takes longer time and is very slow, we advise you to visit the nearest service center with the phone to be checked.