Is there any way to make a parameter "either bool or any other String" when deserializing?

[czy-29]

I tried either, but it didn't work as expected:

use either::Either;
use serde::Deserialize;
use serde_urlencoded::from_str;

#[derive(Deserialize)]
struct ParamEither {
    #[serde(with = "either::serde_untagged")]
    param: Either<bool, String>,
}

impl ParamEither {
    fn print_de(input: &str) {
        match from_str::<Self>(input) {
            Ok(Self { param }) => match param {
                Either::Left(param) => println!("param: bool({})", param),
                Either::Right(text) => println!("param: String(\"{}\")", text),
            },
            Err(err) => eprintln!("error: {}", err),
        }
    }
}

fn main() {
    // output: param: String("text")
    // this is expected!
    ParamEither::print_de("param=text");

    // output: param: String("true")
    // expect: param: bool(true)
    ParamEither::print_de("param=true");
}

The deserialization process did not resolve true to bool.
Is this a bug? If so, is it our bug, either's bug, or serde's bug?
If not, how should I correctly implement this feature?