The idea that there was such a thing as a
Reichsverteidigung tail band probably stems from deductions in Karl Ries's books of 40 years ago, from limited information.
On the photographic evidence, coloured tail bands were adopted by some units operating against US bombers (e.g. JG 1, 11 and 54) by early 1944. My
guess is that these were intended as an aid to reassembly after a pass through a bomber box — various memoirs say that the fighters were all over the sky afterwards.
From memory, bands were seen on shot down aircraft of JG 2 and JG 4 in November 1944 (Field Intelligence Unit reports) while they were employed in support of the army in the West.
The order to apply unit identification bands "for better differentiation in the air" was being relayed around the Luftwaffe in December 1944. See
here.