Thanks so much for mentioning the potential conflict with iframes lazy load and some of the way folks place ads on their sites.

I have finally heard from the top 2 ad agencies who have confirmed that the way they defer their JS to place the ads on the page will keep this from being a conflict, as WP fires its PHP way of lazy loading first. So all good for those folks.

Can't say the same for all of the smaller ad agencies though, but will be asking bloggers who use them to get tested confirmation.