Definition of Annex I, point 21 to Regulation (EU) 2023/826 says that:
‘Motor-operated building element’ means opening or comfort equipment in buildings, excluding ventilation equipment, that can move or rotate, or both, by using input from the mains power source. The motor-operated building element incorporates an electric motor or an actuator and a control unit, and is operated by the end-user through cabled and/or wireless control(s), via a network, or controlled automatically with the use of sensors.’
It results that sensors are part of a motor-operated building element, and that the limits of the regulation are applicable to the entire door or gate. Please note that this may also derive from Annex II point 6, where "gates" or "doors" are in the scope (and not, for example, "motors" or "sensors").
Definitions Article 2(7) and Article 2(5) say that:
‘active mode’ means a condition in which the equipment is connected to the mains power source and at least one of the main functions has been activated
‘main function’ means a function delivering the main service(s) for which the equipment is designed, tested and marketed, and which corresponds to the intended use of the equipment;
It follows that the equipment is in "active mode" when it is delivering a "main function" as described above. While from the information that we have it would seem that the presence of a safety sensor does not constitute a "main function", you (i.e. manufacturers) have more information and might be better placed to assess this.
Furthermore, manufacturers are primarily responsible for assessing the appropriateness of having (networked) standby mode(s) in relation to the intended use of their products. As per the guidance of the standby regulation now in force ((EC) 1275/2008), it is admissible to claim the inappropriateness of the requirements for the intended use of equipment, provided a technical justification is given in the technical documentation. Exemptions on the ground of the inappropriateness for the intended use do not imply that products are exempted from the scope of the regulation. Other requirements, such as information and deactivation requirements, continue to apply. Any claim requires a technical justification by the manufacturer to be included in the technical documentation. The justification cannot be a general statement, but it should be a specific technical description of why the equipment cannot be used as intended for a certain requirement.
Disclaimer: Please note that the European Commission cannot provide a legally binding interpretation of the EU legislation, as this is the sole competence of the European Court of Justice. Any remarks from the European Commission services are without prejudice to the position the Commission might take should related cases arise in a procedure before the Court of Justice.