The mask's filtering performance is certainly at least as good/better than the usual (paper?) disposable respirator masks (which usually only filter particles, but do not have an active carbon filter (which you hardly need for flour dust)).I use the mask mainly as a hobbyist for sanding and varnishing wood, and I can't notice any wood dust or solvents when I breathe in the mask. I think flour dust should not be a problem with the P2 particle filter that comes with the mask.
However, the mask is made of rubber. This could be uncomfortable for a long time in a hot bakery because of sweating.