Odds Xilinx partnered w/Bitmain and would do a pre-emptive release of ther FPGA hardware before this one?
Odds Bitmain got a hold of some of these boards, figured what parts to "hog" and bought the bulk of the stock?
Bitmain uses some smaller Xilinx FPGA for their management boards for their ASIC miners. There is no evidence yet there would be directly making FPGA miners.
All design details of VCU1525 including BOM was public on Xilinx website until recently. So anybody could take the BOM list and try to buy all the stocks of some components.
There was no evidence of their other stealth miners either besides the hash increase.