This server suffered water damage that came from an upstairs bathroom , the top getting the worst of it.
This type of damage is called called "blushing", the same type of effect as when you put a cocktail glass down on a table top and you get a white ring. The water gets trapped between the wood and the finish, causing anything from a faint milky appearance to an opaque whitish effect. This can usually, depending on the severity, be corrected without refinishing. Sometimes it can be repaired in the home and occasionally it will need to go to the shop.
This piece had a very nice finish with a lot of age and patina. In this case keeping the original existing finish was important .