Here is the answer to the new UI one too!
( how to turn off battery charge indicator when the screen is off/ when the screen is locked)
Display: scroll down, turn off SHOW charging information.
Ok now that my 10 plus has updated (today) to Android 10 I now see the option to turn off "show charging information" .
NOTE..... You have to be on Android 10 OS to see this option. So until you've updated your phone to Android 10, you will not see this option!
The charging progress screen is a Samsung attempt to notify the user when the device is fully charged without turning on the screen. It may cause a screen burn, so I resolved the problem by disabling it as suggested and using Battery 100% Ready.
I found the right solution by trting the screensaver one mentioned in this thread. I've done this on an S10E, but I hope it's the same on all devices of this generation.
Go to Settings > Display, and scroll down. The two options on the very bottom are Screen Saver and Show charging information, simply toggle Show charging information to off.