This seems to be based on close to nothing tbh. There isn’t really anything at all that supports this and i doubt even if it did happen, we’d get hardly any information on it as it’s largely irrelevant to the overall plot. I don’t think any particular thing led the ancients to their demise or to the final days. It seems pretty clear and cut that what attacked them was some form of extra terrestrial. We’ve already seen numerous ones such as omega or Ultima, with Ultima even having the description of being able to unfurl the laws of creation or whatever. We also know Omega’s homeworld was destroyed by some mysterious otherworldly entity.