As the reference from this answer from the Stack Exchange developer, displaying Age from the profile was removed from per-site and network profile.
So hence this problem has been solved.
The actual answer from Michael Stum is:
That was an oversight - we removed Age from Profiles ages ago, but still had the code in. When looking at removing the code ...
As Oded has kindly mentioned, the date format is yyyy/mm/dd as also shown in the placeholder:
Somehow I just missed that, thus what I thought is July 11th was actually November 7th as far as SE knows.
The only bug was in my head. Cheers, and hope not many will fall in this same pit. :)