Well-known cultural phenomenon in Europe in which a German-thinking
individual (usually from Germany, Austria, or Switzerland) that you may have never interacted with before notices something distressing and promptly steps out of their comfort zone to 'help' , by systematically lecturing you on
all the things that you are doing wrong about your life and
all the things that you should and are not doing.
A non-verbal form of Germansplainin is also known as the GLOD (German Look of Disapproval)