I think it depends how the rudder pedals are designed. If someone is braking during the take off roll, then something is wrong with him or improper training. On Airbus, you need to apply decent pressure before it will start to actually brake. It happened before tho.
Anyway, I keep my feet up and feel comfortable about it. In case of sudden loss of power on one engine, you would have better control with the feet up. That's one of the advantages. I'm definitely not criticizing people having their feet down on Airbus, I used to do the same and it's totally doable. But
I believe Airbus has designed the rudder pedals for the pilots to have their feet up. At least, that's what the official CBT from Airbus is saying:
https://ibb.co/eJm6MT