It’s all about safety whether you like it or agree with it or not.
https://www.roadandtrack.com/new-cars/car-technology/a32718015/turn-signal-dangers-july-2020/I specifically changed mine from all red to red/amber for earlier information on the matter, over 20 years ago. I never had points deducted for this change, and have been in many judged events. In a Concours one should never receive deductions for safety related items, such as this, or the addition of seat belts on cars that never had them originally.
Unless you are the original owner of a German market car, and know specifically that nothing was ever changed it may a tough call; all red as replacements were unavailable for years. It’s possible that they were changed by a prior owner many years ago.
I'd like to add that a few short years ago, one of our members from Poland was looking for an "original" late 280SL. Turns out one of my friends had one, an elderly German woman who lived nearby. It was a 1971 model, one of the last, and she owned it from new, and used it for daily use for many years. She insisted it was all original, and never crashed or rusted. Well, our Polish friend comes over to Michigan to buy it, and negotiate with my friend, and he bought the car. However in very close inspection it appears that a number of subtle things were changed, and evidence of partial rust and body repairs became evident. Our Polish friend still bought the car, but restored it instead, where other non-original things were discovered. So, even the original owner didn't have full knowledge of what her mechanic did on it, and little recollection of the time she was "tapped" in a very minor rear-end collision 40 years prior...