23 Now there was leaning on Jesus’ bosom one of His disciples, whom Jesus loved. 24 Simon Peter therefore motioned to him to ask who it was of whom He spoke.
Now there was leaning on Jesus’ bosom one of His disciples [John],
The reason the person referenced here is ambiguous is the humility of the apostle who wrote this gospel, the apostle John himself.
whom Jesus loved.
The apostle John’s name never appears in this gospel. The person “Jesus loved” was the apostle John:
Jn 19:26 When Jesus therefore saw His mother, and the disciple whom He loved standing by, He said to His mother, “Woman, behold your son!”
Jn 20:2 Then she ran and came to Simon Peter, and to the other disciple, whom Jesus loved, and said to them, “They have taken away the Lord out of the tomb, and we do not know where they have laid Him.”
Jn 21:7 Therefore that disciple whom Jesus loved said to Peter, “It is the Lord!” Now when Simon Peter heard that it was the Lord, he put on his outer garment (for he had removed it), and plunged into the sea.
Jn 21:20 Then Peter, turning around, saw the disciple whom Jesus loved following, who also had leaned on His breast at the supper, and said, “Lord, who is the one who betrays You?”
Simon Peter therefore motioned to him to ask who it was of whom He spoke.
Peter deemed that John had more influence on Jesus than other disciples, so he asked the beloved disciple to query Jesus regarding who the betrayer was. Another reason might have been that John was reclining next to Jesus.
Jesus loves all His disciples, but some hold distinction in His eyes.
Jesus loves all His children but some hold distinction. The apostle John held that distinction enough to be called the person “whom Jesus loved.” John had a unique relationship to Jesus.
God loves the entire world (Jn 3:16) but love for His own is another category of love (Jn 13:1). Those who believe in Jesus hold a special place in His heart. Even more, some, such as John, held a unique place in Jesus’ heart because of who and what he was. He had the closest friendship to Jesus. John responded to Jesus more than the others. John had a greater capacity to appreciate who and what Jesus was.