It isn't plagiarism if you put your own twist on a recipe or whatever, or if you state your sources (I.e. Give credit where credit is due). It is plagiarism if you copy someone's work word for word, or their photo, and then repost it as your own.
Plagiarism can feel like a grey area at times, but based on @allasyummyfood's description, this seems like a pretty clear case of it. ☹️
I am not saying what the guy posted isn't plagiarism
I just wonder if she would have cared if somone did plagiarism about something not related to food or recipes i.e. something that is not related to what she is posting about
I would guess that it's simply easier to spot plagiarism in topics that a person is interested in.
That is a valid point, but just take a look at this maybe you can see the real motif.