The problem continues to be that Zenyatta just wants to discord the tank, making for uninteresting gameplay. This will fix that by making it comparatively worse against tanks and better against others, since it has a strict damage dealt limit.
Remove the 7 seconds “can’t reapply on this person” timer. Increase discord damage to 35%. When discord orb has caused +100 damage to be taken remove it and start a 5 second cooldown on it. This encourages placing it on characters smaller than the tank, and strongly discourages wasting it on a big barrier. For one second after discord orb is applied, allies can see the target, through walls or not, as a purple figure. This is a much stronger indicator that a person is discorded and will encourage team play aside from shooting the tank.
What if discord just became a damage / reduced healing attack? It would hit do say… 50 damage or so? go on a… i donno 7+ second cooldown? And lower healing by 25% for 5 seconds. So it’s still useful for tanks but not overwhelming