Works produced by lost generation authors often shared which theme

The works of the Lost Generation authors shared a sense of disillusionment that many trace to the destruction caused by World War I. This can be seen in works by authors such as Scott Fitzgerald and Ernest Hemingway.

   Disillusionment, loss of identity and lack of motivation

Explanation:  The term "Lost Generation" originated after the First World War, and refers to generations that grew up during the war or participated in it. These are young people who are disoriented and disappointed under the influence of all the horrors and fears during the war and were unmotivated even to perform the most ordinary daily duties. Thus, in the artistic sense, this term signified a group of writers, poets, artists in general who, after the WWI, were inspired by such feelings and whose themes were mainly demotivation, loss of identity, uncertainty, trauma, disappointment, etc.