Peace be upon you. According to Grand Ayatollah Sayyid Khamenei (may Allah protect him): If the congregation is standing and some people wish to pray individually, it is not permissible if doing so weakens the congregation's prayer or disrespects the Imam whom the people believe to be just. Otherwise, it is permissible to pray individually. According to Grand Ayatollah Sayyid Sistani (may Allah protect him): If it does not disrespect the Imam of the congregation, there is no issue. However, if it does disrespect the Imam and he does not deserve such disrespect, then the prayer is forbidden but not invalidated. May you be successful in all good.