If it is a reference AMD GPU I would imagine AMD would be the one responsible for the warranty process with proof of purchase. It wouldn't make sense to do it any other way. Is there any labeling on the packaging to indicate it is made by a 3rd party, such as a logo for something like Power Color, or any other company?
Ryzen 7 7800X3D, ASUS ROG STRIX B650E-F GAMING WIFI, G.SKILL TRIDENT Z NEO 2x16GB DDR5 DRAM 6000MT/s CL30, AMD Radeon RX 7900 XTX, LIAN LI EDGE 1300, Corsair MP600 PRO NH 4TB