"Absolute" means "unquestionable, fundamental, ultimate, no exception", etc. You've linked to a single study which did not test all forms of IF. You can't say you know something absolutely if you haven't even tested for it.

Specifically, there are much longer periods of fasting which may have a different impact on the result which are not tested for here. There is a claim about alternate-day fasting which is actually not supported in the linked study.

In addition, the longer alternate-day fasting practices may include ad libitum which may have a detrimental effect. Lack of adequate protein is presumed by many to be linked to loss of lean muscle, and the quality and form of feeding during feeding windows would therefore be of high importance, but doesn't seem to be accounted for in these studies.