It's possibly even a double-standard too. Don't we do a ton of stuff that would have been deemed offensive in another age? We have to assume that works both ways. Stuff we do now will one day seem fucked up and offensive.
Also, we can't even be sure which things we do now will seem offensive to future generations. I read somewhere some author making the point, but they assumed the future would just be even more politically correct about the things we're politically correct about now. So, they assumed that some sort of cringe we have about, for example, cultural appropriation now would just give way to a stronger version of the same cringe, later. Maybe using futons or something would seem racist in 20 years, because it's cultural appropriation of Japanese futons, and they're not exactly like the Japanese ones, or something. That was the implication.
But, that's kind of a huge assumption right there: that the future will just be our current biases and trends, but extrapolated. What we can be sure of is only this: some of the things that really offend and concern people right now, will seem extremely silly in 100 years, and some of the things that pretty much everyone thinks are acceptable will seem beyond belief. And, nobody can predict which is which, or even what things future generations will notice about us. It'll be something we find innocuous that future generations think is appalling, and we probably can't even comprehend right now exactly how or why they'll think it's appalling*, but it'll make perfect sense to them. There will be new "isms" by then, and we will be accused of breaking them, in ways we probably can't even articulate yet.
*Although at a guess I'd hazard that us eating meat might be a thing, and they'll be amazed that we get really offended because someone tried on a kimono, on the basis of not offending a nation that harpoons whales to death, and we're probably chowing down on a hotdog while complaining about it. All other "isms" that concern us might just pale before such "species-ism" by which the future defines what they think of our ethics: Oh, so we're super upset that someone made a joke about Chinese drivers? But ... we're a race of ghoulish murderers. (EDIT) Maybe vegans will be looked on more kindly, however, most of them are like "you do you" to the ghoulish murderers. Like if you lived next door to someone who raised children and ate them and you were personally "no thanks I don't much like eating children" but didn't do anything, d'ya think other would look kindly on your abstinence? Maybe the future will look on current non-meat eaters similar to people who turned a blind eye to the Nazis taking Jews away.