We only have one tiny manuscript of the LXX that contains the divine name in the Greek form Yaho (photo above) yet Emanuel Tov, a leading textual critic of the Hebrew Bible/LXX, argues that Yaho was probably the original form of the divine name in the LXX. This is because there is good circumstantial evidence to support the idea. Even if we didn’t have the fragment with Yaho in it, the circumstantial evidence would be strong that the early LXX used the divine name Yaho. Of the earliest NT manuscripts we have, none of them can confidently be dated earlier than the year 200 CE. (See God’s Library: The Archaeology of the Earliest Christian Manuscripts (2018) by Brent Nongbri) By 200 CE the divine name was no longer in use in the LXX, so if it was used in the early NT, then we have no manuscripts from the era before 200 CE which would correspond to the period when the divine name was used. So we don’t have any direct manuscript evidence either way for how the NT handled the divine name prior to 200 CE. We do have manuscript evidence for the LXX in this earlier period and it did use the divine name.
A copy of the NT with the divine name Yaho might turn up one day, but even if it doesn’t there are good reasons to believe the name did occur in the early NT text. Because, if we are being reasonable about it, if Jews used the divine name Yaho in the first century, in their texts and also verbally, as the evidence suggests, then the early Christians must have done so as well because they emerged from the Jewish community. Plus it makes sense of so much of the biblical data that original use of the divine name is key to understanding much about the NT. A striking example is the often quoted Psalm 110 which in the extant manuscripts confusingly reads, “the Lord said to my Lord”, whereas the early LXX, and presumably the NT as well, would have read, “Yaho said to my Lord”. Another is the fact that the meaning of the name Jesus would have been much more intelligible to people who pronounced it as Yahoshua, and who also used the divine name Yaho. The connection between God Yaho, and his sent forth saviour Yahoshua would have been obvious, as apparently it was. (See Matt 1.21 and Acts 4.12)