The first thing I check with a new motherboard is to make sure all the screws for the VRM heat sink are tight. The last motherboard I bought came with loose VRM heat sink screws right out of the box.
The second thing I check with a new motherboard is visually inspect all the copper pins in the RAM slots and CPU socket to make sure none of the pins are bent. That's another common manufacturing defect on motherboards.
I believe the VRM of the B550M motherboard is not the issue because it passed the CPU FPU stress test, Ryzen Master overclocking test, and can run World of Warcraft, Overwatch, and Black Myth: Wukong without problems. I switched back to my old motherboard without reinstalling the system or modifying any settings, and everything returned to normal. Now I can play Battlefield 2042 without issues. I think the root of the problem might lie in the driver optimization for the RX 9070 series graphics card, and it may take a long time for AMD to release a fix. In the end, this issue remains unanswered. That’s it. Thanks to everyone for following this post, and I wish you all a wonderful day. Thank you.
