My daughter had the same thing at 3 years old, during the lockdown last year. It went on for a couple of months and then settled down. An educational psychologist I spoke to said that it is common at that age because they have so much to say that their brain is working faster than they can form their words! It did settle down after a while and now (at 5YO) there’s no sign of it. Definitely keep an eye on it but it may settle down itself.