Planes pararmeter under `frequency_merge` for delowpass is faulty

[srappan]

blur = (1 + 3/8)
delowpass = vsd.frequency_merge(
    [jpbd, cr],
    mode_low=jpbd,
    mode_high=cr,
    planes=[0],
    lowpass=[
        None,
        lambda i: core.fmtc.resample(
            i,
            h=1080,
            w=1920,
            kernel="lanczos",
            taps=[3*blur],
            fv=[1/blur],
            fh=[1/blur],
        ),
    ],
)

Setting planes=[0] should only affect luma, but both chroma planes are also affected.

Screenshots of 'U' plane mode_high

mode_low

merge

[ghost]

Not related to lowpass filter used