Aggregates is changeable because of dependent origination, so nibbāna is unchangeable

1. All conditioner have 3 sub-characteristics (upāda[jāti], ṭhiti[jarā], and bhaṅga[maraṇa]) according to the description of 5 aggregates and 12 dependent originations.
2. Saṅkhāra means cause of effects. This is conditioner aggregate of dependent origination.
   Saṅkhata means effect of causes. This is conditioned aggregate of dependent origination.
   Because saṅkhāra of saṅkhata, have to be saṅkhata of the other saṅkhāra.

So, nothing is no condition, except nibbāna. And that everything, except nibbāna, must be changed (jāti, jarā, and maraṇa) by it's multi-conditioners.