My void-corrupted hex eagle has no Skyriding visual effects, just looks like Steady Flight. Also buff says ‘Increases flight speed by 310%’. Seems that other people were having this issue as well in April of this year.
Also, I’m not having this issue because I don’t have any visual effects toys active but:
Previous bug report states that when appearance modulating toys (void specific?) make the mount no longer void corrupted.