It's not maintenance of a body fat percentage where this is usually an issue, but rather the process of cutting calories to get there that causes muscle catabolism. This can happen at any body fat percentage really (although it is more profound the lower you go). Obviously steroids can prevent muscle wasting during this caloric deficit conditions.
Ive never used AAS just sarms but I got down to about 7.5 % for my first comp and felt pretty ordinary and was a angry mother . I like to sit about 12% most of the year that allows more food and in general strength training progresses best for me at this % .