I've namechanged as it's sensitive
I know a lovely woman who bought quite a bit of product from our business when setting up a cafe a while ago. I wouldn't say she is a friend at the moment but definitely a close acquaintance and on the way to becoming a friend.
Her cafe has done really well, but in the last week or two she has had a new member of staff every time I've been in (owner not present) and to say she's having teething problems is an understatement. She can't make coffee (she thinks a latte is coffee with a splash of hot milk- and I had to correct her when gave me a half full cup, which was cold) , she constantly overcharges even though the prices are written on the wall, and she gets flustered to the point where it makes customers uncomfortable.
AIBU to mention carefully to the owner about this new member of staff? I know from firsthand experience that a new business needs to start strong, and I can see her quickly getting a bad review online.