The gdb version used is embedded in STM32CubeIDE, a customized version of the Eclipse IDE. The problem appears to be in the gdb launch: trying to execute even from the command prompt, positioned in the correct directory: arm-none-eabi-gdb --version takes often tens of seconds.

This makes impossible to start a gdb sessions on the target, because the IDE checks if the debugger is available executing "arm-none-eabi-gdb --version", as can be shown here: