A single judge of Karnataka High Court (Bengaluru Bench) held that along with notice under 41A CrPC (Section 35 BNSS), a copy of the FIR must be sent along.

From Para 9,

This notice does have clarity as to why the petitioner is being summoned. The matter could be disposed of recording the fact that the second notice does contain the crime number, as the issue may seem to be very simple. In the considered view of the Court, it is not, as Section 41 of the Cr.P.C., deals with arrest of persons. Any notice so issued under Section 41-A if not complied with, the Station House Officer is entitled to arrest the noticee. Therefore, the noticee must be aware of why he is being summoned to the Police Station, as summoning to the Police Station is not summoning a person to a happy place. A citizen must know as to why he is being summoned. The information to the citizen cannot be half baked; it must be in full. The notice must contain the crime number and the purpose for which he is being summoned. While it can be transmitted electronically, no fault can be found with that, but it should mention crime number. The duty of the Station House Officer would not stop at mentioning crime number, but he should also attach to the communication, a copy of the FIR, so registered against the noticee, as power is available to summon the accused or any person in connection with a crime. Therefore, the noticee, without knowing the crime number and without getting a copy of the FIR, cannot be asked to appear before an officer of the police station on receipt of notice under Section 41-A.

From Para 10,

Sub-sections (2) to (6) of Section 35 of the BNSS assume significance. Section 35(4) permits issuance of a notice to any person and the noticee shall be bound to comply with the terms of the notice. Section 35(6) commands that if a person fails to comply with the terms of the notice or is unwilling to identify himself, the Police Officer may, subject to such orders as may have been passed by the competent Court in this behalf, arrest him for the offence mentioned in the notice. Therefore, the rigour is little stronger. Stronger the rigour, the noticee is required to know all that he has to reply, prior to his appearance before the Police. It, thus, becomes mandatory for a notice to be issued under Section 35 of the BNSS to mention the crime number, the offence alleged in the crime so registered and necessarily append to it a copy of the FIR so registered, as any person who receives the notice must be aware for what he is being summoned to the Police Station.

From Para 13,

13. It is made clear that till the guidelines/check list is so notified by the State, if any person is necessary to be summoned, the drill that shall be followed are:-
(a) The notice under Section 35 of the BNSS shall mention the crime number and the offence alleged in the crime number. This can be communicated to the noticee either through the conventional method or through electronic mode.
(b) The communication shall attach copy of the FIR so registered, as the FIR would contain the gist of the complaint.
(c) In the event notice does not contain the crime number, the offence alleged or appending of the FIR, subject to just exceptions, the noticee is not obliged to appear before the officer who has directed him to appear and no coercive action can be taken for non-appearance.
(d) It is also necessary for the Police Department to bring about robust system for the FIR being uploaded immediately on their registration and make it search friendly.

Other remedies to police atrocities are here.