Why va" selects whitespace characters before the string?

I've noticed that when I try to select or to yank a quoted string together with quotes (for example by ressing va") it yanks the whitespaces before the opening quote. It's very annoying because usually I do this to copy a string literal from one place and paste it to the other where I have completely different formatting (e.g. from an array of string constants to a fuction invocation). Whitespaces usually just break the formatting and I always need to delete them manually. Why does it happen and is there any way to prevent vim to copy those leading whitespaces?

See the example:

[https://asciinema.org/a/618998](https://asciinema.org/a/618998)