What on earth is the U.S. doing in Syria?

What is the reason?

There is no good one.

The U.S. military forces there just become targets.

The U.S. should not involve the U.S. with internal disputes in Syria.

For some background, see

https://www.fff.org/explore-freedom/article/washingtons-continuing-shame-in-syria/

For the negative effect of our having military forces in Syria (and Iraq), the following makes a good argument::

https://sonar21.com/u-s-inching-towards-world-war-iii-while-biden-administration-hides-u-s-casualties/