How is that a mistake ?
99% of all Nazi uniforms , tunics , blouses , shirts etc were denazified from mid 1945 to problibly 1950 .
I have in my collection around 60 uniforms of all branches of the Third Reich . I have been collecting since 1973 . Of The uniforms , I would say that 45 of them have had the breast eagles or armbands replaced and these uniforms are my keepers , I have owned well over 200 uniforms . Of my political uniforms ...Only ONE has its original armband and that one was missing its
Gebiet triangle ( I have since restored it) .
Go for it and restore it Kameraden .
But remember ...do it right ....Restore it with insignia that matches the condition of the shirt ...you will be pleased with the outcome ...just be patient , it may take a few years .