A 16 bit seed, like 0xBCFE, is also a 32 bit seed, 0x0000BCFE.
Detection was added in October-2024, which explains why the "was this ever contributed" from July-2024 is no longer flagging, and the encounter is better matched.
The BACD_U_AX means: set the two halves of PID with calls A and B in reverse order (B, A), which is different from Method 1/2/4 (A, B). Then IVs are set.
BACD is the call order, `U` is "unrestricted", meaning it can be any 32-bit seed (well, not entirely), and AX means it has "antishiny xor" behavior when creating the PID, with special restrictions on the A call result. The "A" call gets truncated and is xored with the trainer ID and B to ensure it is never shiny.
It's still flagged because the seed 0x0000BCFE is not a valid starting seed to generate the Pokémon.