https://www.merriam-webster.com/dictionary/fascism
Merriam Webster obviously has no political agenda and rightly describes it in non-left/right terms.
Those sources that "define" it as "far right wing" are making a political editorial rather than a definitional effort. Do you suppose M-W jjust "forgot" that it is a "far right wing" ideology? Purposefully left it out? What?
That, of course, is absurd. If such an apolitical definition could not exist, then you might have a point. As it is, all you have is (as usual) propaganda.