Given that vgf2p8affineqb performs an XOR permutation of the input, and that XORs are associated, XORing two values that where transformed in the same manner can be reassociated to happen before. Their immediates also need to be XORed together as well:

gfniXor_src:
        gf2p8affineqb   xmm0, xmm2, 1
        gf2p8affineqb   xmm1, xmm2, 3
        pxor    xmm0, xmm1
        ret

gfniXor_tgt:
        pxor    xmm0, xmm1
        gf2p8affineqb   xmm0, xmm2, 2
        ret

https://godbolt.org/z/16or45959

Most nodes that lower to vgf2p8affineqb already perform this fold so this mostly applies to intrinsics.