> As for plotholes, I believe there is no major one if we assume ridding the world of source is the canon ending
Good one. How about:
a) Red Prince's origin and the whole debacle it raises about the identity of Dragons (whether they were created by Ouroboros as by Patriarch 's words, or regressed into lizards and whatever Zorl-Stissa had to do with the ordeal)
b) Souls and Spirit Vison, Mindread (Source Abilities) being canonically present in Dragon Knight Saga after the so-called 'purge'
c) which should be just b.2 - Dragon Knights and Dragons (who are Source-dependent beings) still existing and utilising powers after the 'purge'. Also the Sentinel Island? The place that manifested consciousness due to an abundance of Source?
a) No that's not a plothole at all the way you say it. I guess what you actually mean is how they devolved into lizards despite being created by ouroboros while the god of lizards is zorl-stissa, in reality
While Zorl-Stissa and the lizards u...hey are not related to the true dragons. But either way a game between dos2 and FoV won't do a worse job of explaining it than a game taking place before DOS2.
b) Nothing I could find on the wiki pages suggests those are source skills. You can see spirits with source, OR you can have silver eyes and see them with those
which is not the spirit vision ability.c) The island's consciousness originated in source and existed since the earliest days of rivellon (didn't manifest in source after the purge), and it's not made clear exactly how it didn't cease to exist or turn into a silent monk after the purge, despite it's origin being in source. Okay, so something that's not really a plothole, about a character that appears twice in a shorter part of the game, that's not major. Also googling about dragon knights being "source-dependent" beings yields nothing. The patriarch not being a silent monk is consistent with slane being purged but not being a silent monk. Allegedly the patriarch's name still holds power despite that being dependent on source, that could be a plot hole but we never see that take place so it could just be a wrong claim by one character and not a claim made by game devs. And because of his "divine power", it's also possible he wasn't affected by dallis or the godwoken attempting to purge the world of source, so you're not demonstrating it's a contradiction. But once again the limits of his power could then be explained by another game before DOS2 and not necessarily a game between the two games which is what I was obviously talking about in my original comment.
If you are confused by this, look up the definition of a plot hole.
