Free transfers were available for Zandalar Tribe from the 4th of February 2022 until the 10th of August 2022.
They gave you 6 months to migrate any character you wanted for free, yet you were unable to take it. It is unfortunate. They will offer you a level 70 boost with the Wrath expansion on Tuesday if you want to reroll on another server, otherwise you will have to pay to migrate.
How many characters that you play are stuck on Hydraxian?