{{echo|[[File:Image-x-generic.svg|right|140px|link=]]}} {{echo|[[File:Image-x-generic.svg|right|140px|link=x]]}}
Looking at data-mw for the above two transclusions, we see the following:
"params":{"1":{"wt":"[[File:Image-x-generic.svg"},"2":{"wt":"right"},"3":{"wt":"140px"},"link":{"wt":"]]"}} vs "params":{"1":{"wt":"[[File:Image-x-generic.svg|right|140px|link=x]]"}}
The peg tokens are not to fault. Looks like it might be something in ext.core.TemplateHandler that sets up params.