I share your opinion. I don’t know, if there is a chance to get out if the icon is default or changed. But isn’t it possible to get out, if the update was succesfull or not? If the new favicon could not be downloaded, don’t change the existing favicon.
Unfortunately, creating the Favicon does not work during the update or by creating new entries.
There is another Thread especially for this issue here: keepass-2-4-0-favicons-when-creating-new-passwords
For some sites it is working when click on “Download Favicon” in the KP database.
I am using “Yet Another Favicon Downloader”, which is working on some situations where the other Plugin brings errors.
Perhaps a look at it helps to discover improvements.
Thank you for your work