Imagine you are a popular content creator on PixelFed, many followers, but many stalkers also. You don’t want people to know where you live. One day you post a picture of the sun out of your window. Exact time is attached in metadata. Assuming GPS metadata is stripped, can someone, using inclination of the sun to the horizon, Nautical Almanac and some math calculate your latitude and/or longitude, and to what precision? Assuming also meteorological data archives on cloudiness, etc.
Latitude can theoretically determined by the data in your picture (although a picture of the clear night sky would be better). Longitude is much harder, because you can’t really tell how far east and west you are based on the angle of the sun alone. This was a historic problem, especially when mankind started traveling across oceans.
The problem can be solved by knowing your time relative to some reference point. This is how Greenwich Observatory became so important to timekeeping: to determine longitude, ships had to carry a good clock that showed them what time it was at Greenwich, and the difference in time between when the sun was directly overhead on the ship and noon at Greenwich told them their longitude.
So, the main piece of information that gives away your longitude is actually the timestamp, assuming it is either stored as UTC or as local time with a UTC offset, because then you have an idea where the sun is and can relate it to noon UTC. (A date and UTC offset also indirectly discloses what time zone you are in…)