John saw angels being given the seven bowls of judgment in the heavenly sanctuary, which became filled with the smoke of God’s unapproachable glory.

Revelation 15:5-8

5 After this, in the vision I saw in heaven the temple that ◄corresponds to/was represented by► the tent that the Israelites pitched in the desert. That was the tent that contained the Ten Commandments. The temple door was opened {was open}. 6 The seven angels who had the bowls containing the seven plagues came out of the temple. The angels were dressed in clean, white linen garments, and they wore gold bands around their chests. 7 One of the four living creatures gave each of the seven angels a golden bowl, filled with wine/liquid. That wine/liquid symbolized that God, who lives forever, would severely punish rebellious people. 8 The temple was filled with smoke that symbolized the presence of the glorious and all-powerful God. No one was able to enter the temple until the seven angels finished pouring out the seven plagues.