I would say Jan meant the red background for the white eagle. The T-34/85 belonged to the Polish 4th Armour Brigade of the 1st Armour Corps in 1945. Although the red background seems to be correct for the Polish emblem it looks like it is not this time. I would say the emblem was applied with the white paint only. Below here is a pic of a Polish T-34 marked in the same way. The red background can't be noticed though.