In terms of rarely acknowledged, even in spaces and among groups where discussion of privilege does take place? Right-handed privilege. So many little things in society are set up for right handers in ways that they would not even think about. Scissors and serrated knives will cut awkwardly. Lecture desks can be physically uncomfortable to use (I've even seen suggestions that this can lead to chronic injuries later in life, though cannot substantiate that). Even our writing system makes using a pen or pencil much harder for lefties, resulting in the physically-awkward adaptation known as "hook grip" (especially if they do not have teachers who can relate to their experience and guide them through it). As recently as Gen X at least, it was not uncommon for lefties to be beaten to be forced to write right-handed.

It's obviously insignificant compared to cishet white male privilege, but those definitely do get acknowledged so I figured that's not what the question is asking. I also think it can be very worth exploring these lesser-known privileges, even if they are lesser in significance as well, because they can provide a lens through which to teach people about privilege that is more removed from politicisation, and can help them accept the idea of privilege as a problem. (That's what this article did, to great effect IMO.)