The spec reads for absolutely positioned elements

If only one inset property in a given axis is auto, it is set to zero.

This would imply, that if the size in the same axis is not specified (i.e. auto), then the element would be resized, since now both sides are set to non-auto values.

For example, with the current spec I'd expect the following box to be full width instead of max-content wide. In other words, it would be equivalent to having uncommented the line right: 0.

<div class="abs">Hello World</div>

.abs {
  position: absolute;
  background-color: lightgrey;
  left: 0;
  /* right: 0; */
}

Since this is not the case, I suppose this is a bug in the spec.