Jewish here well versed on the bible
That change is BULLSHIT
Slavery was Slavery, in fact, there are rules about What to do if a slave reach Cannan (Israel), because everyone Who set foot on the promised land, is free by default
Slaves back then have their ears cut, head shaved and sometimes marked, thats why a slave cant be free, because People knew who are slaves, and was a serious crime hiding a slave in other areas outside of cannan
And sure, there was SERVITUDE, a kind of slave who after 6 year they become free and choose to stay, but they are still SLAVES
It never stop amuse me how People try to re write the bible, ignoring the era and know nothing about it
I'm not saying it was necessarily right, it was an imperfect solution to an imperfect world, same with the system we have now. I wasn't ragging on ancient Israel, they were far more enlightened than any other people of their time. But slavery still existed in their land. I probably know more about Israel during the NT times, unless you've also studied the NT like I have. Slavery/servitude/bond servants (whatever you want to call it) were common, common enough to have teaching about it for the early Christians, whether they were master or slave.
It was rare that Israel operated under the Mosaic law fully as I'm sure you know (multiple occupations, civil wars, rebellion against God, most of the nation taken in captivity to Babylon etc, much happened that was forbidden during these times, in fact they were the rule, not the exception, at least from my research, very rarely was the nation faithful like they were under David and Solomon's rule.
I don't think the change was bs at all, keep in mind they only changed it in a couple of places in the NT, clearly in the context it was speaking about something quite different from the slavery that most think about today, as I mentioned.
Back to my point, much of what we call employment today deviates very little from what they called slavery/servitude at one time, it just has a reskin.