Answer

Saaiduna Abu Juhaifah Radiallahu Anhu narrates that the Prophet of Allah Sallallahu Alahi Wasalam said, “I do not eat leaning.” (Sahih Bukhari p.812 v.2)

It is severely disliked to eat leaning on the wall etc if it is done out of pride and arrogance. However, if it is not done on pride and arrogance it will be permissible (mubah). (Fatawa Hindiyyah p.337 v.5)

Only Allah Knows Best