بسم الله الرحمن الرحيم
This is one of many prohibited innovations if the perpetrator takes it as a consistent practice (constantly performing it after every prayer), whereas the sunnah after the obligatory prayer is to remember Allah by seeking His forgiveness, bearing witness that there’s no deity in truth except Him, glorifying Him, praising Him, and exalting Him. Also invoking Him by yourself (not in a communal supplication) with what is authentically reported (in the text) without raising the hands just as the Prophet -sallahu alayhi wa salaam- would do and he would not raise his hands during supplication after the obligatory prayers. Thus this should not be done due to it opposing the sunnah and consistent adherence to it is an innovation.
Translated by Najeeb Al Anjelesi
Source: المنظار في بيان كثير الأخطاء الشائعة