Yes, I have noticed this since January. I believe the comments are only visible to you, not potential guests. I have gotten two such comments "bathroom smell" and "shower." One benefit is that guests can comment exactly what led them to give you the rating. Cleanliness seems to be the hardest hit aspect across the listings I've surveyed over the past year. There is so much that can go wrong or unnoticed, and people have different standards of cleanliness, so don't take it too harshly! I haven't noticed from my experience that this has invited low ratings; it has actually been the opposite in my reviews: fewer 4 star cleanliness but the comments have been more like gentle suggestions!
I have started monthly thorough cleanings: wash all the blinds, baseboards, fan blades, minifridge, picture frames; weekly dust bookshelves, sweep/mop under beds/funiture. Some guests will go to great lengths to catch a dust bunny and report you!