Why has Mars never been terraformed?

Idk if anyone has asked this before, but I don't think I had ever thought about it before. Terraforming missions are routine in the 24th century, colonizing barren worlds to make them type K or terraforming them is routine, and I assume this has already been done on at least dozens of worlds; but not on the Red Planet? I mean, there were well-populated bases (until 2385) on Mars, in addition to the Utopia Shipyards in the atmosphere, but the planet itself was the same as it is today. Is there any explanation for this?

After the invention of the warp drive, the next logical step for humanity would have been to terraform Mars, which would take perhaps less than 100 years in our (very late) universe, but would be a viable goal to colonize another planet in the solar system. It's strange to see several class M worlds inhabited and similar to Earth, while our red neighbor remains the same as it is today. I thank you in advance for any help. ♥️