You are asking about the collective dhikr: is it a bid'ah (religious innovation), such as saying the adhkar together with the sisters in unison?

Question:
The time is for Ghada, who has a letter of four pages in large format. These four pages contained nine questions. All of these questions revolve around the sea of bid'ah (religious innovations), as she has seen much and much of what she is certain is from the bid'ah. So she asks first about the collective dhikr: is it a bid'ah, such as saying with the sisters together in one voice, "La ilaha illa Allah" or other such adhkar, or Surah Yasin in one voice? May Allah reward you with good.

Answer:
There is no doubt that the remembrance of Allah (Glorified and Exalted is He) is prescribed and required, and it holds great virtue. Indeed, Allah (Glorified and Exalted is He) said: However, the remembrance of Allah is to be done in the manner prescribed by Allah (Glorified and Exalted is He), and in the way that the Messenger of Allah (peace and blessings be upon him) and the generations after him practiced it. What about the blessed generations that the Messenger of Allah (peace and blessings be upon him) praised?
Because every Muslim remembers Allah, Blessed and Exalted is He, with the prescribed dhikr, in the places where dhikr is prescribed, such as after the five daily prayers, and in the hours of the night and the hours of the day. But every Muslim remembers Allah for himself, without being linked to others, or with a collective voice, or with one person reciting and the rest repeating what he says. If these characteristics are present, they are characteristics of bid'ah (religious innovation), for which Allah has not sent down any authority. Yes.