Positano - Casa Guadagno: 2 Star?

The booking.com rating I see is "excellent" (8.6)

1J. Star ratings, review scores, and quality ratings

We don’t assign star ratings. Depending on local regulations, they’re assigned (a) by the Service Providers themselves or (b) by independent third parties (e.g. organizations that rate hotels). Either way, star ratings show you how Accommodations measure up in terms of—among others—value, facilities, and available services. We don’t impose our own standards for star ratings, and we don’t review these star ratings, but if we become aware that a star rating is inaccurate, we’ll ask the Service Provider to either prove they deserve it – or adjust it!
https://www.booking.com/content/how_we_work.html?aid=397594&label=gog235jc-1DCAEoggI46AdIM1gDaLQCiAEBmAExuAEXyAEP2AED6AEB-AECiAIBqAIDuAK-0KKfBsACAdICJDI5MWU1YTFjLWE4NzQtNDQxNC1iNTAyLTNlYzQ4OTJkMmFlMdgCBOACAQ&sid=5c75a57eb0616d0436eb814573035ff4&srpvid=eafd3e292fcb01f2&

The 'star' rating seems to be how 'fancy' ( or how many extras it has ) not how 'good' it is

The star rating for this accommodation is exactly as Joe explained it: in this case it is based on amount of amenities and services provided and not cleanliness and comfort. It's a guesthouse that doesn't have a restaurant or bar, pool, spa, shuttle service, business center or any of the other extras that kick a star rating up.

So it terms of star ratings, a 4-star hotel may have a bunch of extras but be noisy, have stained furnishings, surly staff, a dirty pool and so on. The humble two or even 1-star accommodation may be lacking in extras but offer clean, comfortable rooms for a good price. That's where reviews/popular opinion ratings from former guests come in: as you could see, those guests rated Casa Guadagno very highly. Make sense?

https://www.cnbc.com/2022/12/11/what-do-hotel-star-ratings-mean-heres-a-breakdown.html