@David1632
Yes, that is low in Airbnb's book. Although they do not communicate this to guests, and therefore plenty of guests are going to leave a 4* review thinking that is good, the minimum requirement is supposed to be 4.7*. or above (4.8* for Superhost). See below:
Now, that's not to say that they suspend or delist every host that doesn't maintain 4.7* or above. There are plenty of listings on Airbnb that fall below this requirement. However, if you keep getting lower ratings, especially on things like cleanliness, then yes, they may do that.
I had a perfect 5.0 star rating for two years (and 4.9 or above for a few years before that), but last year I got a 3* review and received an automated message from Airbnb telling me to improve my standards or that they might suspend me. Now, I knew they weren't actually going to do that just because of one low rating, especially as my average was still over the 4.7* requirement, but if I kept getting lower ratings they might have done.
I know it doesn't seem fair. The guest above thought that 3* was good. Luckily for me, she asked Airbnb to remove it once she realised that 3* is not good at all!