The original Pathfinder 2e core rulebook (2019)'s first printing errata says:

• Page 459: In the first bullet point under Knocked Out and Dying, change the sentence to “You immediately move your initiative position to directly before the turn in which you were reduced to 0 HP.” This was originally intended, and prevents weird situations where you are knocked out by a reaction and die without having a chance for your allies to help you.

The Player Core, p. 410, says:

• Move your initiative position to directly before the turn in which you were reduced to 0 HP.

The Player Core, p. 443, says:

• You immediately move your initiative position to directly before the creature or effect that reduced you to 0 Hit Points.

Let us assume that the Player Core, p. 443, is erroneous.

What happens if a creature is reduced to 0 on their own turn? For instance, suppose the initiative order looks something like this:

• Enemy A

• Enemy B

• PC A

• Enemy C

During PC A's turn, they take a Reactive Strike or persistent damage and are dropped to 0. Does the initiative order stay the same, or does the initiative order proceed to enemy C, and then become something like this?

• Enemy A

• PC A

• Enemy B

• Enemy C