Not sure if it's an Exploit or bug!

During the event of egghunt I noticed something peculiar when my inventory eggs reached 999 yet decided to keep looting eggs to see what would happen! The results were that it would either lock me from looting greens or blues eggs and drop a higher tier or not drop anything!

Time passed and a friend of mines said he noticed he locked himself out from looting copper chests due to the fact that he had 999 on his inventory so he either would loot silvers or gold ones! We decided to try an experiment and see what would happen if he had 999 coopers and 999 silvers and oh boy it was marvelous! Again not sure if it's a bug or a glitch but with a full team this thing can be exploited in a scary way!

I'm not sure what you're thinking is an exploit here? If a boss can drop a copper, silver, or gold chest, but I have 999 copper chests and 999 silver chests, and a copper chest or silver chest would drop, it just doesn't show up. It doesn't make you get a gold one instead if that's not what would have dropped.