Format letter missing in DATE

when I enable showing date forma it shows like this

[ATTACH=JSON]{“data-align”:“none”,“data-size”:“full”,“title”:“2019-01-03 17_49_35-main_menu.jpg”,“data-attachmentid”:85953}[/ATTACH]

it is missin “Y” and is confusing to users

2019-01-03 17_49_35-main_menu.jpg

Hello,

Can you tell me the steps to reproduce this bug?

What is the application and type of field for example…