Great news! Thanks for taking the time to post an update with your findings. I suspect the fix was this change:
The current implementation of "Flash Mode=RAM" was meant to syncronize the startup of the microcontroller with an application launched by AppLab.
However, it has a bunch of limitiations which make it basically useless for bigger projects.
Arduino Apps now use the new Startup mode > Wait for App configuration of the UNO Q board instead of the previous Flash Mode > RAM configuration:
Thank you all for your responses 
One question:
Monitor.begin();
delay(10); // <------ for outputs on IDE "Serial Monitor" 9600-speed
// The following I have used to get faster outputs on the UART:
Serial.begin(115200);
Serial.println("\033[2J\033[H Hello world, STM32U585 has started ...");
delay(500);
The output has been visible below of the Zephyr trace on Putty terminal:
*** Booting Zephyr OS build v4.2.0-46-gb34bcdbc3f9f ***
Since the update the output is not visible anymore. What has changed? I want to add my own logging system and need a faster UART.
use Serial1 now for external output, Serial is now mapped to Monitor..
~q
Thank you, trace is now working.