I have a Beelink U59 model and S/N:

My BIOS has never been updated since purchase.
Based on the dmidecode output you provided:
BIOS Vendor: American Megatrends International, LLC.
BIOS Version: JTKT001
BIOS Release Date: 03/09/2022
BIOS Revision: 5.19
I’ve been using Debian 12 with Kernel 6.1.0 and other distributions with this kernel for over a year now and it works perfectly.
But the problem is that I tried to install Debian 13 and the screen freezes and keeps flashing, even in the installer! I checked and the same thing happens with Fedora Workstation 42 that I tried to install. It seems that it doesn’t support the new Kernel 6.12 LTS.
I would like a position and solution.