That's pretty unfortunate for the blog author, can imagine making that kind of mistake early in the morning will really wake you up.
The blog doesn't mention specifically whether the author had uploaded using a Lemmy app or the webui AFAICT - if he used an app, there are some that actually store the auth/delete token returned by image uploads, and provide a section within the app where you can manage/delete (purge) images you've previously uploaded to Lemmy
Yeah. It uses google ad-mob, or if you purchase it needs the google play store app to verify that and deactivate ad-mob.
A way to purchase it without going through gplay would fix this, and probably means it could be published on fdroid in a premium-only version at least. I've been meaning to ask @rmayayo@lemmy.world about the feasibility of that for a while now. It's bothered me for years now, but I simply couldn't find an alternative so far (neither back on reddit in the days).