I got this information from here.😳
So basically, Lord Vishnu was pleased with Bali Chakravarthy's greatness but still had to punish him for wanting to make the demons the Kings of the world (because then adharma would prevail over dharma), so he pushed Bali into patal lok but then gave him a boon that due to his good deeds, he would become the Indra of the next manvantara (8th one).
The name 'Indra' is only a title. Each Indra has his own name and each manvantara has a different Indra.
Does anyone know the name of the current Indra?