@libreoffice: Oops, due to not expecting nag screens to be repeated by default, I read the "Do show again" as "Do not show again". (Or did that change?) I nevertheless would expect a "No" button regardless of the checkbox being checked or unchecked.
And indeed, there's neither libreoffice-gtk3 nor libreoffice-gtk4 installed. Then again I'm probably old enough so that I didn't consider the design to be outdated. I also start LibreOffice with the soffice command due to being used to that. ๐ง๐ค๐งโ๏ธ