What controller are you using...?
There's honestly only so much that can be done when there are some weird driver-related issues that cause triggers to work completely differently on some systems entirely arbitrarily, even for the same controller, but at least if I know what controller you're using I'll have some idea what's going on and if there might be some kind of solution.
I see... I see... that's probably the issue due to how the game's controller support works. If you use some sort of controller rebinding program (booting the game as a non-Steam app through Steam might work), you might be able to get the game's controller support working with your controller that way.
I could potentially, in the near future, test to see if the game even needs an adapter to use a Switch Pro controller, the input handler I'm using may have already handled that out the box, but I'm not 100% sure. And I'm not sure the Switch Pro controller even works properly at all on PC without some kind of adapter or program, so I'm not sure there's any kind of solution here other than that.
I hope one of us can find some sort of solution (either on your end or by fixing something on the game's end or something else like that), and barring that, can live with weapon switching on the face buttons or enjoy the game on keyboard + mouse, depending on what your circumstances are in why you're using a controller and the specific choice of controller in question.
