The author of Revelation thought that very soon the end would come. The writing stresses this throughout. The author even alludes to Daniel to show the nearness:

Rev 22:10 And he said to me, “Do not seal the words of the prophecy of this book, for the time is at hand.

This was written just under 2000 years ago. This sentence alludes to Daniel, which was written when the end was far off:

Dan 12:4 “But you, Daniel, shut up the words, and seal the book until the time of the end; many shall run to and fro, and knowledge shall increase.”

This was written 600 years before the Revelation verse was written. Here is the problem: If greater than a 600 year lapse between Daniel and Revelation is not near the “end” then when Revelation says the end is near that should not exceed the 600 years when the end was not near.

Daniel – “the end is not near”
Revelation (600 years later) – “the end is near”
Modern times (2000 years later) – the end has not come

The face value reading of Revelation shows the author believed the end was near:

Rev 3:10 Because you have kept My command to persevere, I also will keep you from the hour of trial which shall come upon the whole world, to test those who dwell on the earth.
Rev 3:11 Behold, I am coming quickly! Hold fast what you have, that no one may take your crown.

Note that this part is written to the church of Sardis, a church that no longer exists in a city that no longer exists.

Revelation has not been fulfilled in the timeframe envisioned by the author. Either the prophecy was modified, postponed, or cancelled.