Sometimes it is a pain to get your head around what a manuscript actually reads, especially when there are corrections involved. The image below is from the Codex Ephraemi rescriptus 'C', though it is only 'rescriptus' here in Acts 23:6 because of the erasure.
The question is on νεκρων [εγω] κρινομαι.
A clear erasure is visible under the rewritten letters εγω κριν, and possibly also under the following ο. The next two letters -με (itacism for -μαι) seem to me written on virgin material.
1) The erased area is long enough to contain κρινομαι, but we don't know this for sure.
2) Initially I thought that this must have been a correction in scribendo, but this is not clear at all - the space after the original reading is likely to have been blank anyway, leaving room for the corrector to rewrite as εγω κρινομαι.
3) The letters -με may not have been written by the original scribe. I do not know the hands in this manuscript well enough, but there seems to me enough difference to assume this. (Knowing the spelling patterns of the scribe and correctors would help).
4) That the original scribe wrote κρινομαι instead of εγω κρινομαι, is a likely guess (since there are few alternatives), but this is not visible enough to make this a Cvid reading.
5) NA27 had Ephaemi supporting εγω κρινομαι as follows C(*), while NA28 has C2. The latter does not give us an idea what C* wrote, and this is probably correct. How to represent this in a full critical apparatus, is a tricky problem, I don't think you can avoid putting in a note that the erased area matches the length needed for just κρινομαι. And that might help Vaticanus 'B' (the only Greek witness that justifies the square brackets in the NA texts) getting out of its isolation at this point - Ephraemi might have read simply κρινομαι, with Vaticanus.