A pretty severe exploit was discovered in Destiny 2 this past week, which allowed players to instantly recharge their super ability without having to do anything, thanks to a bug with the Telesto pulse rifle and a humble grenade. As such, the weapon has now been completely disabled within the game.
The exploit, which you can see below, involved shooting the ground - as it's ammo does not immediately detonate, all the user then had to do was throw a grenade into the area where the various projectiles lay, and once it exploded, your super bar would be near enough, if not completely full. The exploit was possible in PvP and PvE modes, which gave players who knew the exploit a serious competitive edge.
Players with the Ashes to Ashes perk were able to leverage the exploit even further, as it gives additional super charge with grenade kills - as such, combined with the exploit, this may explain why you may have encountered players constantly engaging their super, and wondering just how they were doing it...
While Bungie have officially confirmed the disabling of the weapon, which they call "temporary", there is no word yet on when it may return, although they have promised to post further updates as their dev team investigates. Stay tuned to GameFront for any more news on this as we learn it.