Hi! I don't entirely see the difference between removing 1 debuff and a layer of debuff (sorry if I didn't completely get the question), but I will try to answer it the best I can. There is a difference between removing all debuffs and one layer of debuffs.

The layer of debuff is removed by a priority order, you can find the order at which they are removed below:

A) Slow, Immobile, Acupuncture, Paralysis, Blindness, Sleeping

B) Chaos

C) Ignite, Poison

D) Imprison, Tag

based on the information written above, debuff of a higher group (for example, A - Immobile) will be removed before debuff of a lower group (for example B - Chaos).

Now for those keen to find out more, some of you might ask what happens if there are multiple debuffs from the same group. Well the debuff that was applied last will be removed first. Even if the debuff is reapplied, it will not change the initial order of removal.

Hope this helps!

~Jib