It was deleted and replaced on 19/12/18 by another altered alteration for 18/12-21/12/18, timed 06:33 ex Kingham. That in turn was deleted and replaced by another one today 20/12/18, still timed at 06:33 ex Kingham and still valid until tomorrow (currently). These variations presumably do differ in some other respects; I've not looked to see.
The screens at Kingham yesterday & today still seemed to think it should be 06:20. Luckily, I don't need to catch it tomorrow! I'll be very glad if it reverts to 06:23 - three minutes more in bed is important to me at that time in the morning, and much to be preferred to spending an extra three minutes sitting at Charlbury waiting for the line to clear.