Logs that are sent to Grafana/Loki contain body in base64

[ym-project]

The problem: Grafana/Loki received logs with encoded to base64 body

Is it ok for open telemetry? Or something went wrong?
Below you can see my code snippet:

use opentelemetry_otlp::{LogExporter, WithExportConfig};
use opentelemetry_sdk::Resource;
use opentelemetry_sdk::logs::{SdkLogRecord, SdkLoggerProvider};
use opentelemetry::InstrumentationScope;
use opentelemetry::logs::AnyValue;
use opentelemetry::logs::LogRecord;
use opentelemetry::logs::Logger;
use opentelemetry::logs::LoggerProvider;

let log_exporter = LogExporter::builder()
  .with_http()
  .with_endpoint("http://localhost:3100/otlp/v1/logs")
  .build()
  .unwrap();

let resource = Resource::builder().build();

let provider = SdkLoggerProvider::builder()
  .with_batch_exporter(log_exporter)
  .with_resource(resource)
  .build();

let library = InstrumentationScope::builder("service_name").build();
let logger = provider.logger_with_scope(library);

let mut log_record = logger.create_log_record();
log_record.set_observed_timestamp(SystemTime::now());
// ...
// A lot of strings like log_record.set_...
// ...
log_record.set_body(AnyValue::Bytes(Box::new(
  record.args().to_string().into_bytes()
)));

println!("{:?}", log_record);
logger.emit(log_record);

I check log_record before call emit(), and here result

SdkLogRecord { event_name: None, target: Some("reqwest::connect"), timestamp: None, observed_timestamp: Some(SystemTime { tv_sec: 1748874574, tv_nsec: 973140679 }), trace_context: None, severity_text: Some("DEBUG"), severity_number: Some(Debug), body: Some(Bytes([115, 116, 97, 114, 116, 105, 110, 103, 32, 110, 101, 119, 32, 99, 111, 110, 110, 101, 99, 116, 105, 111, 110, 58, 32, 104, 116, 116, 112, 58, 47, 47, 108, 111, 99, 97, 108, 104, 111, 115, 116, 58, 51, 49, 48, 48, 47])), attributes: GrowableArray { inline: [Some((Static("module_path"), String(Owned("reqwest::connect")))), Some((Static("file"), String(Owned("/home/ymdev/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/reqwest-0.12.18/src/connect.rs")))), Some((Static("line"), Int(753))), None, None], overflow: None, count: 3 } }

As you can see, body field is not base64, it's string with content starting new connection: http://localhost:3100/
And then I don't know how to debug opentelemetry functions. But something happens after logger.emit(log_record);

[ym-project]

I tried to replace set_body content to AnyValue::String

log_record.set_body(AnyValue::String(StringValue::from(record.args().to_string())));

And base64 body was fixed. Could somebody explain why AnyValue::Bytes have the problem?