Just bought MB-339, question about speed changes

I purchased the MB-339 and on the marketplace page it says its top speed is 558mph.

In the hangar it says that the max speed is 296kias or 340mph. I’m new to the game so I’m not really sure what would cause the difference.

Also, I was watching some youtube videos and they showed the MB-339 having a cruise speed of 280ktas (indicated in the hangar screen), but mine reads 250ktas.

Did they make changes to the aircraft’s speed since it was added to marketplace?