To my critical thinking, it is an invalid concept, why?
First, I divide concepts into valid or invalid kinds.
A valid concept is one that at least is possible to imagine a concrete event where the concept is objectified - in the imagination i.e. of man.
An invalid concept is the opposite of a valid concept, for example, an invalid has within itself contradictory features, like a non-existing existing cat at the same time in the same place and in the same sense of the animal cat.
Now, an "infinite regress of causation" cannot be imagined at all by man, as it is still regressing infinitely, so why at all talk or debating about its existence, when its existence is not yet in itself completed as to have come to existence - on that basis it is a self-contradictory idea or what I call an invalid concept.
It might be imagined that an "infinite regress of causation" is in a circle, that is also an invalid concept to my critical thinking, because again the causation is not yet completed, no matter that it is in a circle.