He claims it's based on the use of wrong nomenclature. The Navi 21 XT itself reportedly has a stock GPU power of 235W and the total board power (TBP) of the Navi 21 XT reference card is said to be around 320W. Custom models are expected to have a TBP of 355W.
Igor's report also mentions that the cut-down Navi 21 XL has a stock GPU power of 203W and a TBP of around 290W. AMD will reportedly sell a GPU + memory bundle to its add-in board partners, which will contain the Navi 21 GPUs and Samsung 16Gbps GDDR6 memory modules (K4ZAF325BM-HC16). However, AIBs will be free to use other modules.
Lastly, the article mentions that the first custom-design Radeon RX 6000 series cards are expected around mid-November with more volume expected by the end of November. The official reveal from AMD is slated for October 28th.