[RPG] Losing constitution scores in battle; does it bring down the hp and how?

ability-scoresartificerdnd-5ehit-points

So, I run an artificer in my one campaign that just reached lv 20. Part of the lv. 20 ability (Soul of Artifice) reads:

If you’re reduced to 0 hit points but not killed outright, you can use your reaction to end one of your artificer infusions, causing you to drop to 1 hit point instead of 0.

My artificer is using one of his infusions to replicate the amulet of health magic item which requires attunement and reads

Your Constitution score is 19 while you wear this amulet

If my character is about to be knocked down to 0 hp, and then uses his reaction to end his infusion that created the amulet, what happens?

This post is Related but I feel is still different since in this case I need to know if things would happen any differently in this case since it happens instantaneously in the middle of combat, which was a question that the other one did not have to answer, so think of this as more of a follow-up to that one based on new rules

Best Answer

Your hit point maximum may be reduced, but you will have 1 hit point.

The Hit Points rules say:

If your Constitution modifier changes, your hit point maximum changes as well

Changing Constitution modifier does not affect your current HP unless your max hp is reduced to below your current hp.