If someone's max HP is reduced by the Harm spell, then Feign Death suppresses that disease, what happens if they're healed and then Feign Death ends?

Question

The description of the feign death spell says, in part (PHB, p. 240):

If the target is diseased or poisoned when you cast the spell, or becomes diseased or poisoned while under the spell’s effect, the disease and poison have no effect until the spell ends.

Part of the description of the harm spell says:

If the target fails the saving throw, its hit point maximum is reduced for 1 hour by an amount equal to the necrotic damage it took. Any effect that removes a disease allows a creature's hit point maximum to return to normal before that time passes.

Here is a hypothetical scenario:

1. Have harm cast on a player character (reducing the target's maximum hit points)
2. Cast feign death on the character, suppressing (not removing) the effects of the disease (and thereby removing the reduction to the character's maximum hit points)
3. Restore missing hit points (e.g. via cure wounds, now that their maximum hit points are no longer reduced)
4. Wake them up (i.e. cancel feign death)

When feign death ends, does the character's hit points stay as they are (at their regular hit point maximum)? Or are their hit points reduced back down (effectively taking damage again)?

Answer 1

Your current hitpoints cannot exceed your maximum hitpoints.

The important clause from feign death is:

the disease and poison have no effect until the spell ends.

So the effects of the disease are only temporarily suppressed by feign death and if feign death ends before harm, the effects of harm return. In particular, your hit point maximum is reduced to what it was before feign death was cast. When this happens, your current hitpoints cannot exceed your maximum hitpoints, so these would be reduced as well:

A creature's current hit points (usually just called hit points) can be any number from the creature's hit point maximum down to 0.

Hypothetically:

1. Current HP 100/100
2. Hit by harm, take 20 points of necrotic. Current HP 80/80
3. Cast feign death on self. Current HP 80/100
4. Get healed¹. Current HP 100/100
5. Feign death ends. Current HP 80/80

Your maximum HP is your maximum HP, you can’t have more than your maximum except by having temporary hitpoints in addition to your actual hitpoints.

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¹ Note, if the particular spell used to restore hitpoints is the spell heal, the effects of harm would end in toto, and your hitpoints would be 100/100 when feign death ended.