I am not 100% sure based on my readings. Do Interrupt Actions always use a Quick Action (unless something specifically says that the Interrupt can be made without spending your own action)?
Usually the rules specify that something is a 'quick interrupt action' (e.g. Sudden Strike, Luck Control, Guardian talent) or that it is made 'as a quick action, on your turn or as an interrupt action' (e.g. Barrier, Nullification, Quickness). Or even more specifically in case of Blocking and Dodging ('is an interrupt action and occurs out of turn. It does require a quick action however'). These all seem clear cases: the interrupt action also consumes one quick action from you.
But just because this is being specifically pointed out in some cases, you might argue: if this is not mentioned specifically, maybe an interrupt action does not always requires a quick action to be spent?
Sometimes there are specific mentions. For example, Warning Call and Guidance specify that the target can use an interrupt without using their own action. But this can be just a case of 'specific beats general', meaning that these only work because the special rule explicitly states that a target can do this.
A few times, however, the wording of the rule does not explicitly state that the interrupt action to be used is a quick action or not. For example, Quick Travel, Intangibility, Untouchable Speed, Quick Teleport just mention that something happens as an interrupt action, without referring to it being a quick interrupt action. As I also cannot find a general definition or rules section for all interrupt actions (just for specific ones), I am not 100% sure.
Although I would probably say, unless an explicit wording says different, all interrupt actions should require spending a quick action.