Why doesn't the parameter 'strength' in GlowFilter have no effect in TextField in openfl html5?

Why doesn’t the parameter ‘strength’ in GlowFilter have no effect in TextField in openfl html5?

strength
The strength of the imprint or spread. The higher the value, the more color is imprinted and the stronger the contrast between the glow and the background. Valid values are 0 to 255.
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For example, I have an instance txt of TextField, and when I use GlowFilter, setting the strength number to 10 does not work. I have always been puzzled
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Setting strength to 10 also has no effect!
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txt.filters = [
new GlowFilter(0xff000000, 1, 6, 6, 10)
];
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So I can only stack a few GlowFilters
txt.filters = [
new GlowFilter(0xff000000, 1, 6, 6, 2),
new GlowFilter(0xff000000, 1, 6, 6, 2),
new GlowFilter(0xff000000, 1, 6, 6, 2),
new GlowFilter(0xff000000, 1, 6, 6, 2),
];