fascism its self is not a very slippery term, there are maybe 3 academic definitions of fascism, these are incredibly similar to each other, and are in some cases literally only semantically different, these are almost universally supported by academics (as long as you ignore the people literally calling for eugenics and ethnostates)
and yes, just because someone or a group may match one point on these definitions doesn't make them fascist, but when they routinely fall under the vast majority of fascist traits, they just might be... fascist