Right out of the gate I can see an issue with the wording of misfire:

Misfire: Firearms that have been improperly cared for or subjected to unusual strain can misfire. If you attempt to fire a firearm that was used the previous day and that hasn’t been cleaned and maintained since then, attempt a DC 5 flat check before making your attack roll. If you fail this misfire check, the weapon misfires and jams. The attack also becomes a critical failure, and you must use an Interact action to clear the jam before you can reload and fire the weapon again. Once you’ve spent at least an hour cleaning and maintaining a weapon, you don’t need to roll for a misfire until the next day unless an effect says otherwise. A weapon can also misfire as a result of using a specific ability.

Upon a misfire triggered by a feat it could be interpreted either way:

1) It misfires, needs an interact action to clear the Jam, any future attacks are now at DC 5 flat check to misfire again and requires an hour of cleaning to remove the misfire flat check

2) It misfires, needs an interact action to clear the Jam, future attacks are as normal.

I think it's compelling that they intended that it would be the first, but the wording isn't concise enough to exclude the second as it only says that a weapon that needs to be maintained or feats can cause misfire and the effects of a misfire is a critical failure and jamming, not requiring a flat check on subsequent firing. The major reason I think it's the first is the wording in the first sentence:

Firearms that have been improperly cared for or subjected to unusual strain can misfire

If it indeed is the first something like this could clean it up, but I'm sure there's other ways to reword it:

Misfire: Firearms that have been improperly cared for or subjected to unusual strain can misfire. If you attempt to fire a firearm that was used the previous day and that hasn’t been cleaned and maintained since then or you haven't cleaned your weapon since a previous misfire, attempt a DC 5 flat check before making your attack roll. If you fail this misfire check, the weapon misfires and jams. The attack also becomes a critical failure, and you must use an Interact action to clear the jam before you can reload and fire the weapon again. Once you’ve spent at least an hour cleaning and maintaining a weapon, you don’t need to roll for a misfire until the next day unless an effect says otherwise. A weapon can also misfire as a result of using a specific ability.