According to Wikipedia, 26 incidences of children killed by dogs in the UK since the turn of the millennium. That's in addition to rather more adults so killed, although the deaths of children tend to be more publicised.
Depending on your perspective, that makes such deaths quite rare: a little over one a year. It's less, for example, than the number of people killed by defective toasters every year. Or it's also 26 deaths too many.
The numbers seem to have increased sharply since 2020 – it's a small sample so too much shouldn't be read into it but I at least started thinking of dogs acquired from rescue centres since Lockdown. Also, a brief purely subjective analysis suggests that many of the dogs were of breeds sought after by a young men of a certain disposition for fighting and 'protection'. Quite a few of the dogs' owners were described as uncles of young children, which fits that pattern.
While there are some attacks that aren't easily explained and some that happened when dogs and babies were left alone together for minutes while the owner dealt with an emergency. I was also struck by the number of victims who were owners killed while having an epileptic seizure, including one where the dog, a rottweiler, had not attacked as such but appears to have attempted to pick up her owner by the scruff of the neck as she would one of her own puppies.
It's probably impossible to stop such attacks altogether but there does seem to be a clear pattern of irresponsible ownership and the deliberate unlicensed breeding of aggressive dogs for fighting. It's an old but true saying that there are no bad dogs, only bad owners.