Alejandra 1.5.0 adds spaces to all lines inside multi-line comments, including empty lines:

{
  /*
   This is a comment.
   
   This is the second paragraph of the comment.
   */
}

This may not be apparent unless you select the text, but the “empty” line in the middle of the comment actually contains 3 spaces after formatting. Such lines are considered to be suspicious by many tools (e.g., even git diff highlights them as whitespace errors).

Maybe Alejandra should leave such lines completely empty instead of adding whitespace-only lines to the code?