I emailed Charlie Stoever, and he successfully reproduced the situation from the Ezoic side.
It appears that progress on this matter has stalled, so let's streamline our approach.
Concerning the sidebar placeholder, I have set the maximum ad width to 300px (I temporarily disabled the previously active Large Rectangle [336x280] for testing purposes). However, wider ads continue to display, even on larger screens, contrary to my specified settings. Is there an automatic configuration that might be influencing this?