Acrobat Reader text extraction issue for tagged document

I observe a strange text extraction behavior in Acrobat Reader for the specific documents. The documents are tagged so generally all paragraph text lines are extracted as a single line. But in some cases the paragpraph text is extracted with line feed. Some experiments shows that it may be related to a presence of a form XObject inside an artifact content.

Is it a but in Acrobat Reder? Or am I missing something?