PointValuePlot can't generate vector figure when set ColorFunction->"Rainbow"

It’s amazing that 12.2’s new function PointValuePlot can’t generate vector figure when I set ColorFunction->"Rainbow". Then I save the figure as PDF, I am sure it’s not an vector figure. Is this due to my computer problem? How to solve it if I want to use ColorFunction->"Rainbow"?

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Code:

PointValuePlot[
    RandomReal[{0, 1}, {100, 2}] -> RandomReal[{0, 100}, 100],
    ColorFunction -> "Rainbow",
    FrameTicks -> None,
    FrameStyle -> Thick
]

Very Thanks!

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Update

Steps:

1. Use the aforementioned code, you can get a figure, then generate a palette from this figure, you can use Alt+P+P as shortcut key.

2. Save this palette as pdf, and observe whether it is an vector figure.

According to my experiment, this problem only occur with ColorFunction.

Example Figures:

1. No ColorFunction
   

2. With ColorFunction
   

pl = PointValuePlot[
   RandomReal[{0, 1}, {100, 2}] -> RandomReal[{0, 100}, 100], 
   ColorFunction -> "Rainbow", FrameTicks -> None, 
   FrameStyle -> Thick];

pl // shortInputForm // Short

Export["PointValuePlot.pdf", pl // Normal] // SystemOpen