Yes you are correct, many, I would say very many have changed their behaviour, some have gone as far as to change their thinking too.
But very many have not, very many people still carry with them the racism of the society they grew up in. We frequently see examples in posts on this forum.
Very few British people are openly racist. (I’ve underlined that so as to ensure my views are not misrepresented).
However, far too many give scant attention to how racism occurs and goes un challenged, or is used as a tool in political and public policy campaigns.
On top of that there still remain overtly racist political groups that have significant public support.