there were the slow mo upskirt shots when she was fighting
You’re saying that being able to see a woman’s underwear when she’s fighting is the same as the Panty Fighter trope, which it is not.
In the Panty Fighter trope, the whole goal is for girls to fight in such a way that the audience can see essentially as much underwear as possible, and the underwear is as small as possible, to maximize pervy male fanservice. There is no reason for them to be wearing as small an outfit as they are besides the amusement of the male audience and to make panty shots “realistic”.
The shots are framed so that there is no real way a normal point of view would ever be able to catch this much gratuitous underwear, regardless of how skimpy the outfits are. Panty Fighter characters are also subject to unrealistic poses such as the Boobs and Butt pose and the Broken Back pose, which further maximize the showing off of their “assets” These are all part of the stereotypical male gaze angle.
Essentially, the difference lies in the intent.
When Diana and the Amazons are fighting, they have a very acrobatic style. Maybe because after hundreds of years of no war they needed something to keep training exciting, but probably because it looks super awesome. So as a result of the fighting style you do see their BLOOMERS (seeing as it’s not just underwear, they are wearing bloomers, just like cheerleaders do.) But it’s not meant to be a way to tantalize the audience, because the scenes are not framed that way. It is only because it’s a direct result of their moves and their outfits.
(I assume this is what you meant with “slow mo upskirt”)
In all of these shots, the eye line is not directed towards their underwear, it is drawn to the actual move itself. The high kick, the stomach kick, and the flip are the focus of these shots, not the panty shot. And the only reason you even see the bloomers is because of their skirts.
But why are they wearing skirts? They could all be wearing pants! They just wanted to sneak in panty shots!
The reason they all wear skirts is because their costumes are modeled after pteruges, the pleated leather skirts Greek warriors wore. You’ve seen them in Gladiator, basically any movie about Jesus, and of course, Xena.
They wear them because not only are they Greek warriors, they are quintessential Greek warriors.
Honestly, the Spartan warriors in The 300 are more scantily clad and subjected to the male gaze than the Amazons are. Just look at these unattainable male fever dreams.
TL;DR - Seeing the bloomers of an Amazon as she’s roundhouse kicking someone in the face is not the same as a gratuitous panty shot, none of the Amazons are subject to the male gaze, it’s apples and oranges.