why disable the quic in CronetEngineSingleton?

in the file: CronetEngineSingleton;

why disable the quic, if do this, glide still only use http2 but not http3? even if I integrate the dependence:

implementation "com.github.bumptech.glide:cronet-integration:4.14.2"

private static CronetEngine createEngine(Context context) {
return new CronetEngine.Builder(context)
.enableHttpCache(CronetEngine.Builder.HTTP_CACHE_DISABLED, 0)
.enableHttp2(true)
.enableQuic(false)
.build();
}