Other than the dealer you recently purchased your Celica from, It could have also probably been the previous owner.
Your door panels should also match the same as your front and rear seats.
If your front seats do not match the same material as your rear seats, its obvious that they had been swapped from another Celica at some time (or reupholstered). This could have been due to water damage, a stained/destroyed seat, or just a replacement by previous owner for personal preference.
The stock Celica GT door panel insert is cloth/mesh: