I would definitely recommend trying to pay more attention maybe to him as he may feel jealous. My son has gone through this stage more so with “unintentionally” hurting my little girl like pushing her away at times or being abit too rough but I’ve tried to focus on positives rather than being negative and putting the attention on him. Not sure if that could work for you maybe ask what he would like to play with and encourage you all playing together. 😊 sorry I’m not that helpful but I hope it helps.
If he goes to nursery, speak to them to direct you for support. While it is normal for siblings to get jealous, I would speak to them for guidance x