In John 8:14 there is a textual variant between Η in the NA28 versus ΚΑΙ in the Byzantine text:

ὑμεῖς δὲ οὐκ οἴδατε πόθεν ἔρχομαι  Η ποῦ ὑπάγω

ὑμεῖς δὲ οὐκ οἴδατε πόθεν ἔρχομαι, ΚΑΙ ποῦ ὑπάγω.

Now concerning Papyrus 39, the Münster Institute and the NA28 say 𝔓³⁹ reads Η, while the IGNTP says it reads ΚΑΙ.  The NA28 does not even put a “vid” with it.  But only the right edge of the last letter of the word is visible to me.  It is rounded, not a straight up and down line like it would be for H or I. But the scribe’s Epsilon is round, and it seems more likely to be an E than Η or I, thus perhaps ΟΥΔΕ.  Is the theory that there is only room there for one letter, like H?  However, it certainly does not look like an H. (Image posted below, the 2nd line ΠΟΥ ΥΠΑ with the letter in question barely visible before that.)

The NA28 text in English is “but you do not know where I came from or where I am going.”
The Byz text in English is “but you do not know where I came from and where I am going.”
𝔓³⁹ if ΟΥΔΕ in English is “but you do not know where I came from nor where I am going.”