John 8:14 New International Version
14 Jesus answered, “Even if I testify on my own behalf, my testimony is valid, for I know where I came from and where I am going. But you have no idea where I come from or where I am going.
John 5:31 – New International Version
31 “If I testify about myself, my testimony is not true.
I appreciate Jesus may well have had witnesses / or did not even need witnesses. However, that does not get away from the fact that John says at at v14 doesn’t need witnesses and at v31 he does need witnesses.