This doesn't work at all for me:

my @arr1 = (2, 34);
say "34" if @arr1 ~~ 34;

#no output...??
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This works for me. (it says "34")

This doesn't work either:

my @arr1 = ('hello', 'goodbye');
say "array size is 2" if @arr1 ~~ 2;
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This also works as documented (no output except warnings about comparing numeric value with strings)