In the latest update, there was a new aiming system for mobile players which also is included in the new GUI update which happened today. The concept of aiming using a bubble typically for mages and hunters are brilliant especially on mobile platforms. However, with new improvements comes with new bugs and glitches. I have recently discovered that sometimes, after you use a ranged attack (for example such as Mage Bomb), your aiming bubble remains stuck and goes with you wherever you go. Occasionally, after several uses of this, it will stack and cause your game to lag. These bubbles will only disappear through leaving the map or the game. Additionally, pressing the ranged attack icons multiple times can also create this problem where the bubbles will stack up again. My suggestion is that you can develop a timer to determine how long each aiming bubble lasts to prevent them from being cluttered and stuck to your screen forever.
Above as you can see here, It suggested on discord that the developers should add a line of code to fix cluttering transparent bubbles from stacking on each other.