If you stop qualifying for a feat after obtaining it, do you lose it?

[Squiggit]

I assume yes, but I can't actually find a rules citation that agrees with this and would appreciate help finding one.

The description of prerequisites in both the glossary and the rules section of the book only mention taking feats, not potentially losing them later.

[Hsui]

"A character might need to retrain several options at once. For instance, retraining a skill increase might mean they have skill feats they can no longer use, and so they’ll need to retrain those as well." CRB p502 under retraining

This says that if you don't have the necessary skill level after you initially took the feat, you cannot use a skill feat which has that as a prerequisite. While it does not provide explicit guidance for other feats/features (e.g. what happens to an AC if you switch orders), the logic would be that you check for a prerequisite change whenever something happens to your character.

So you do not actually lose the feat, it is rendered inoperative. You would need to retrain to actually replace the non-functioning feat

[Squiggit]

That mostly works. Wish there was something a bit more explicit, especially since there are ways to lose prerequisites outside of retraining now (a Hellknight who stops being lawful, for instance).

Weird that it's in the retraining rules and not in the rules on how prerequisites work.

[David knott 242]

I think you just lose the use of a feat if you no longer qualify for it, not the feat itself. If you managed to regain the prerequisite before retraining away that feat, you would immediately be able to use that feat again. I do not recall ever seeing anything that contradicts this interpretation.

[graystone]

"Prerequisites: Any minimum ability scores, feats, proficiency ranks, or other prerequisites you must have before you can access this rule element are listed here." So with this, you'd lose access to the feat but access isn't losing the feat itself: it's there but locked until you once again meet the prerequisite or retrain it.

For instance, look at this action:
Arrest a Fall, Reaction
Trigger You fall.
Requirements You have a fly Speed.

Anytime you gain a fly speed you can use it and when you don't you can use it. As "every creature can use basic actions except in some extreme circumstances", it always available when the conditions are met. Losing/gaining prerequisites for an action seems quite similar to losing/gaining it for a feat.