I think we really have to do a bit of study of history. Jesus when he entered Jerusalem saw a vision of what would happen in AD70 when Jerusalem would be destroyed.
He told the people to flee to the mountains. Escape. ‘Pray that it does not happen during winter’. Leave Jerusalem. I can see the writer of Hebrews saying the same thing. ‘Your city is not the current one’ ‘you have moved to Zion and no longer on Sinai’. A warning not to return to the Temple sacrifices.
The writer in Hebrews also keeps telling the Jews to go “outside” the city.
However there were these freedom fighters who told the Jews that they would preserve the Temple. They would win over the Romans. There would be “peace and safety”. They stay behind. They did not heed the words of Jesus. These freedom fighters are what the Jews term as “messiahs” at that time.
As a result of their belief in these false Messiahs, they chose to remain in Jerusalem and protected the Temple and their faith. The Romans took siege of the city of Jerusalem. They were trapped and could not get out.
Those who believe Jesus escaped. Know that this is how we should read verses pertaining to ‘false messiahs’ ‘peace and safety but their ruin will surely come’ ‘there he is, don’t go there’ ‘heaven and earth disappears’.