JPD
Retina and Rollei user
Too perfect, if you ask me. Given that the finder and taking lenses have different makers and will not share the glass formula it is surprising that they should develop the same bloom. Chances are that that is a after-market coating upgrade. These were quite popular and accessible in the 1950s.
Natural bloom has a rainbow shine, like oil in a puddle of water. The after-market coatings would be blue and uniform.