None of those were mass stabbings.
Jake Davison (Plymouth incel) - shooting
Derek Bird (Cumbria) - shooting
Liverpool van driver - van (unusual he was white, no fatalities)
Michael Ryan (Hungerford) - shooting
Thomas Hamilton - shooting
Harold Shipman - injections
Lucy Letby - injections/intravenous
Stabbings aren’t inherently worse or better, they’re just a different means to commit an atrocity.
Statistically mass stabbings, as opposed to stabbing of only one individual in any attack, are seemingly not the murder means of choice for white British men. So it isn’t unreasonable for people to assume that a mass stabbing incident, if declared terrorism (which this was at first) is likely to have been carried out by someone who was neither white nor Christian.
@Yellowcardigan ’s statement “Of course British/white/Christians commit crimes, but generally not this type of crime in Britian,” is, I imagine, in reference to the fact that the victims were injured in a mass stabbing, not that they were attacked in general.