You're not alone with this, I can see if that if it's a non-default user photo you get this output:
With as img path of "/applications/core/interface/file/index.php?file=/monthly_2019_01/Untitled-1.png.26edcbdc76a12029d2e3edbe1899c2c9.png" (404 Not found)
Where as default photo and other areas of the user photo which do work follow the URL format of:
"/uploads/monthly_2019_01/Untitled-1.thumb.png.a0ff1c23cd7642d033c2e300aa049c01.png"
Seems to only occur in the author panel (cAuthorPane_photo) on forum content.