Revelation 18 - The plagues she will receive pertain to her idolatry.

Rev 18:4
And I heard another voice from heaven, saying, "Come out of her, my people, that you may not participate in her sins and that you may not receive of her plagues;

It would appear that this warning comes after the destruction of the Whore of Babylon. This same warning was given when Babylon was destroyed.
Jer 51:6-7 Flee from the midst of Babylon, And each of you save his life! Do not be destroyed in her punishment, For this is the LORD’s time of vengeance; He is going to render recompense to her. 7Babylon has been a golden cup in the hand of the LORD, Intoxicating all the earth. The nations have drunk of her wine; Therefore the nations are going mad.

The plagues she will receive pertain to her idolatry.

Jer 51:47-48 Therefore behold, days are coming When I shall punish the idols of Babylon; And her whole land will be put to shame, And all her slain will fall in her midst. 48“Then heaven and earth and all that is in them Will shout for joy over Babylon, For the destroyers will come to her from the north,” Declares the LORD.

The warning to flee Babylon is given two more times in Jeremiah.

Jer 51:45 “Come forth from her midst, My people, And each of you save yourselves From the fierce anger of the LORD.

Jer 51:50 You who have escaped the sword, Depart! Do not stay! Remember the LORD from afar, And let Jerusalem come to your mind.
In chapter 18, we see the judgment of the Whore of Babylon.

Many have speculated that Babylon would be rebuilt in the last days because this chapter speaks of a rich Babylon after the time of John. But Elohim said through the prophet Isaiah over 2500 years ago that the city of Babylon will never again be inhabited (Isaiah 13:19-22). There have been attempts to rebuild the walls of ancient Babylon, but it is certainly not inhabited. Pictures of it today show it to be a desolate hollow place where only jackals might live.

Using Scripture and historical context, we can see who exactly is (was) the Whore of Babylon! (Hint) What do you know of the history of the Byzantine Empire?

Watch and see if you don't agree!