Well, this isn't good. The Heroes of the Storm map Tomb of the Spider Queen map apparently has been broken since the most recent patch (which included D.Va to the game).
The bug in question causes Web Weavers to not use their AoE attack which clears waves, and thus makes the objective significantly weaker. This almost makes the objective not worth doing on the map, which is counter to how most Heroes of the Storm games go.
The bug was discovered by a Redditor named EverydayFunHotS, and addressed by HotS Community Mananger Araxom shortly thereafter, who said that Blizzard would look into the bug.
To make matters worse, though, is that Heroes Global Championship matches were played without the Webweavers using this ability. Such an issue of competitive integrity for the league could have far-reaching implications if Blizzard verifies that the issue was, in fact, a bug and not just a glitch.
These issues could, in theory, call the results of matches that used Tomb of the Spider Queen into question (like this one between B-Step and Team Freedom) - though whether or not matches would be replayed is also subject to some debate. While it does make the objectives somewhat less effective, Tomb of the Spider Queen is also known as one of the less impactful maps when it comes to securing objectives.
Typically, the Heroes dev team is good at notifying teams if there's a known bug and disabling maps in advance, but it looks like this one slipped past them.
Regardless, now that Blizzard's aware of the issue, though the map isn't yet disabled for competitive play, and should be hotfixed soon. Blizzard has not updated with a timeframe just yet, or released any other comments on the bug yet.