Haafiz Ibnu Hajar (rahimahullah) mentions:

Even when commenting on the status of the different narrators and criticizing them, Imaam Bukhaari (rahimahullah) adopted extreme caution in his speech, as will be apparent to anyone who studies the works of Imaam Bukhaari (rahimahullah). Hence, most of the time, Imaam Bukhaari (rahimahullah) would criticize a person saying, “The Muhadditheen have remained silent regarding him (i.e. they have not approved of him),” or, “There is a problem with him,” or, “The Muhadditheen have avoided him,” or other similar remarks.

(Hadyus Saari pg. 480)