Hi, devaluation is a rank 2.5 debuff. Think the game will show it as rank 3 due to rounded values.
Some tests:
-prophecy does not prevent
-miko gohei cannot remove it
-cure cannot remove it
-dispeller cannot prevent
-plague doc fume does not cleanse
==> beakmask prevent
==> bloodletting prevents
Pandemic can spread the debuff
Luckily tom has a video to back up this: