6 and the angels who did not keep their own position but abandoned their proper dwelling, he has kept in eternal chains in deep darkness for the judgment on the great day.
“and the angels who did not keep their own position” These angels were not the ones who fell with Lucifer in the beginning, before God created men on the face of the earth. They fell in the days of Noah [Genesis 6:1-4] according to 2 Peter 2:4-5 which says, “4 For if God didn’t spare the angels who sinned but cast them into hell and delivered them in chains of utter darkness to be kept for judgment; 5 and if he didn’t spare the ancient world, but protected Noah, a preacher of righteousness, and seven others, when he brought the flood on the world of the ungodly”
The fallen angels in Jude 1:6/Genesis 6 were so bad that they received God’s judgment immediately. I believe that these angels are the ones who are mentioned in Revelation 9 as the Locusts. In the Book of Revelation, demons will be released from their prison in hell [abyss] to torment those who rejected Jesus and have the mark of the beast for 5 months.