So did I. Both readings are not true. One is the word of God, the other is not. I go with f35, P66 and the common reading of the Greek texts. "being ended" γενομενου
Which creates a conflict for you.
13:2. Two textual variants control discussion of this verse: (a) the manuscript evidence for the present participle ginomenou and for the aorist participle genomenou is very evenly divided. The former is often taken to mean that the meal was ‘in progress’ (hence ‘during supper’, RSV), but might mean that it ‘was being served’ (NIV); the latter is often taken to mean that supper was over (‘supper being ended’, AV), but could be interpreted to mean that supper had just been served. Verses 4 and 26 make it impossible to believe that supper was over, and for that reason many prefer the present participle. Conversely, that makes the aorist participle the harder reading (especially if it is understood as in the AV), and for that reason intrinsically more likely to have been changed by a copyist. It is therefore attractive to suppose that the aorist is original, but that it should be understood to mean that supper had just been served (an instance of what has traditionally been called the ‘ingressive aorist’).
D. A. Carson, The Gospel according to John, The Pillar New Testament Commentary (Leicester, England; Grand Rapids, MI: Inter-Varsity Press; W.B. Eerdmans, 1991), 469.