Dunno, but encouraging teachers to check themselves and the ways they interact with kids is valuable. Don't know how often it happens, but this is one of the reasons posited for why black boys specifically start to fail at school from age 7 onwards - the lack of attention from teachers, including the lack of being told off.
If these kinds of unconscious biases are there, they can only be solved by consciously trying to solve them.
This stuff very easily becomes polarised. Progressive stacking is criticised and 'you should be colour-blind' is substituted. But it is very easy to think you're colour-blind when you're actually not.