datetime->ref_count == 0 when using VideoTimeCode

I attempted to attach VideoTimeCode meta to a buffer like in a buffer pad probe:

let datetime = glib::DateTime::new_now_utc();
let video_time_code = gst_video::VideoTimeCode::from_date_time(
    gst::Fraction::new(30, 1),
    &datetime,
    gst_video::VideoTimeCodeFlags::empty(),
    0,
).expect("vtc");
gst_video::VideoTimeCodeMeta::add(
    buffer.make_mut(),
    &video_time_code.try_into().expect("video_time_code")
);

and found that it was outputting a ton of

GLib-CRITICAL **: 21:34:41.068: g_date_time_unref: assertion 'datetime->ref_count > 0' failed
GLib-CRITICAL **: 21:34:41.099: g_date_time_ref: assertion 'datetime->ref_count > 0' failed

suggesting something wrong with how references are counted in this code.

Sorry for not providing a self-contained reproducer here, let me know if you end up having a hard time reproducing and I'll see if I can whip one up.