That is probably a mistake. I was using Street Complete and probably thought the marker was on the street rather than the sidewalk -- I recall having done some street-specific tasks around there. I don't think there are any atypical sidewalks in that area.

Thank you for correcting my error. I looked up the information on the MTA website and submitted my correction for review. See source:

https://bustime.mta.info/m/index?q=305103