When did you buy it? After a cursory search it seems that Xerox engages in the same scammy behavior with 3rd-party consumables: artificially degrading the quality (lower DPI, fake printhead jerks), region-locking, wasting ink so it drains faster, and DRMs that blank out refuse anything that didn't pad their bottom line.
Jerking print heads for laser? That's not how laser printers work. Either way, I'm using 3rd party toner in mine (6515) just fine. It looks like people who have issues purchased metered printers.
Laser heads can misalign though (not sure if Xerox does that). Your Xerox® WorkCentre 6515 printer was launched 9 years ago and is not sold anymore. It's very possible that they changed their practices since then and/or that the price point is high enough that they wouldn't do that (it's aimed at professional customers after all).
Either way after a quick Reddit search there seems to be irreplaceable parts on that printer too. For example the fuser which is allegedly not user-replaceable.
Not if it only happens on 3rd-party cartridges combined with the fact that Xerox claims that they are low-quality and compared to their high quality genuine original cartridges™
