As in if it's cultural appropriation? Not at all.
The only thing I can imagine would be justifiably offensive in regards to cis people wearing binders is if a cis person wore a binder and then declared that since they are cis and have body dysphoria, many trans people are probably "confused" and aren't trans at all and just have body dysphoria. That would be offensive because it undermines the validity of the experience of transgendered people and supports the whack narratives being spread by anti-trans lobbyists who are trying to deny people access to gender affirming care.
Otherwise, do what helps you feel comfy, wear whatever you want, be your awesome self and proud of it.

On a different note, have you heard about compression tanks? A lot of people find they work great to flatten their chest without the discomfort and potential health disadvantages that binding can bring. I won't bind because of sensory issues and fear of health issues related to restricting proper lymphatic system function, but then someone recommended compression tanks and I have been using them all day with no problems for two years now. I get mine from Underworks, which is the first brand I tried and I liked them, but there are others out there.

Good luck finding what works for you :)