23 It will seem like a false omen to those who have sworn allegiance to him, but he will remind them of their guilt and take them captive.

Read Ezekiel 21:23 Using Other Translations

And it shall be unto them as a false divination in their sight, to them that have sworn oaths: but he will call to remembrance the iniquity, that they may be taken.
But to them it will seem like a false divination. They have sworn solemn oaths, but he brings their guilt to remembrance, that they may be taken.
The people of Jerusalem will think it is a false omen, because of their treaty with the Babylonians. But the king of Babylon will remind the people of their rebellion. Then he will attack and capture them.