Please, consider removing the splash screen. It was getting in the way of the final stages of the installation when it's asking for 'Allow Access'. Very VERY annoying.
Thanks for all your valuable feedback @damain! I have also noticed this exact issue with the interference between the splash screen and Windows Defender Firewall dialog and reported it to the Arduino IDE 2.x development team.
I don't so much mind the splash screen. The thing I didn't like is that the transparency at the bottom of the splash allows me to see the buttons on the dialog, but I can't click them! This might be dependent on display resolution, so maybe doesn't affect all users.
As for the general subject of the user experience of the splash screen, there is a report here:
There is now a dedicated issue for the interference of the splash screen with attempts to multitask while waiting for the IDE start up, with a specific mention about the firewall dialog overlap discussed in this thread: