Hi, I can confirm this bug. The systems boots with 'nomodeset'.
0c:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Vega 10 XL/XT [Radeon RX Vega 56/64] (rev c1) It works fine with linux-image-4.19.0-4-amd64 (4.19.28-2) and linux-image-5.0.0-trunk-amd64 (5.0.2-1~exp1) Thanks