Appropriation has different meanings.

If you’re presenting yourself as some activist online or IRL but never actually participate anything or even know what the meaning and history behind the outfits/slogans, then yes it’s appropriation.

The other one is people benefitting from another’s culture without the consequences (e.g. white people with dreads having little consequences socioeconomically, luxury brands “elevating” a subgroup’s “inferior” garment). But the thing is, people are being targeted and harassed for wearing a kefiyah regardless of their culture, race, nationality, etc. You’re benefitting from solidarity and just having a cool garment, but you also won’t be hiding from the unfortunate reality of potentially being a target to fascists.

Your name, skin color, race, etc. may shield you in other situations, but when you wear one, you quite literally become the enemy of two states. I say this 100% sincerely that pro-Palestine people have a lot more to risk than any Zionist.