Roy had made the Gate of the Abyss in Frostfire City himself.
If he had left through the gates that other demon kings had left in the Abyss, it might have been better. But he had left through the gate of Frostfire City… Because he was only a demon lord when he created the Gate of the Abyss, he did not think too much about it at the time. The energy given to the Gate of the Abyss could only accommodate him passing through it at the time. However, he had not expected that it would be fine when he went through, but when he returned, he had advanced.
It was not easy for a creature with extremely high energy to pass through any spatial gate because their energy often affected the stability of space. Now that Roy had advanced, the energy in his body had far exceeded his expectations when he designed the Gate of the Abyss, causing him to be stuck even though the Gate of the Abyss had expanded to its limit.