I may be wrong but I don't see evidence that Youtube continues showing ads on demonetized content like these explicit Ukraine war videos. The reason is that the advertisers who pay money to Google don't want their brands associated with certain types of lurid content. (See Adpocalypse: https://www.google.com/search?q=biggest+advertisers+abandon+...)

So, Google is being extra strict with ads on these videos to avoid an angry call from a giant advertiser like Proctor & Gamble complaining, "Why are you showing my dish soap ads on a video of a naked guy getting killed while pooping?!?" (E.g.: https://www.tubefilter.com/2018/04/20/pg-resumes-youtube-spe...)

There also may be some confusion about some videos with ads and creators not getting the money: the creator has not been accepted into the Partner Program for revenue sharing. Yes, in those cases, the creators are not getting ad $$$ -- even for safe advertiser-friendly videos.

But these Ukraine demonetization videos seem more like not repeating the Adpocalypse debacle and Google will not run ads on them.

Of course, Google/Youtube's system isn't perfect so there will be false-positives. Will there be indecent videos that Google improperly display ads on? Yes. Will there also be high-quality channels that got unfairly demonetized even if advertisers would have no objection to their content? Yes.