Are you referring to the Bible?
This is one where I can see how people would be discomforted by the resemblance to the way the Curse of Ham has been used. This is one where I think it does walk a fine line, because it is getting into interesting ideas of a species that has this darkness baked into its spirit, at the very least has an anger response that is radically different from humans, and that can be interesting. But it can also get into very dark territory and I can see how someone might see it in the game and wonder if the Curse of Ham was something that inspired it. I think you can do stuff like this in a setting, but I also think it's a valid concern to respond to. In one of my own settings the elves were created as slaves for the Ogres originally (that is why they are immortal).I thought it worked, it wasn't invoking any kind of real world racial issues or slavery in my mind but was more based on mythic ideas about elves, humans, ogres, etc all being created by different gods and having fundamentally different natures.
But I get the concern. In real history this was one of the major justifications for slavery in the US---the view that black people were descendants of Ham who had been cursed to servitude). I don't think this is as wildly out of left field as "half" is problematic or "killing things and taking their stuff is a colonialist trope". This is something where you are playing with mythic imagery, and it is easy to see how some people will see that connection.
Personally I think the Mark of Gruumsh is more about having the difference between these beings really matter and also trying to emulate something like the Warf trope (not saying it was specifically Warf being modeled but it does seem made to make that kind of characters: and I think that sort of character is entirely fine). This is one though where I think having a discussion about it is definitely a lot more reasonable than many of the other criticisms of D&D that have taken hold.
The way I would put it is when I made my elves as slaves, I had the thought "I hope people don't misunderstand this" and it wasn't because I thought people who did would be unreasonable. So I would have been happy to clarify my intentions to people with that one. But there are other criticisms where your thought is more "I think people might misunderstand this even though its pretty clear I am not doing anything wrong here", and that is the thought in designers heads I am more concerned about. You make the mark of Gruumsh in a game, fair enough, the Curse of Ham was a thing that was used to explain slavery, I can see a line to it, so I would anticipate responding to any concerns raised (I could even see a writer saying, maybe its too close so I won't do it).
For me it is more about do you need to have a lesson on an entire hermeneutic before you read something and see there is a problem with it, or can you just go in without that and see the issue. If the latter, then, even if it's not what the writer was intending, it's at least a criticism I can understand. This is why the 'going into dungeons and taking things from goblins is a colonialist trope' is so egregious. You need a pretty thorough education in colonialism and literary criticism to even get there in the first place (not a literal college degree education but someone has to explain these concepts to you). Mark of Gruumsh, anyone familiar with slave history in the US (and most Americans are) would at least know what is being referenced when someone raises the concern----though I would qualify that by saying there probably are a larger number of people who don't know about that use of the Curse of Ham than folks may realize.