Hello there ,
I was using the favicon generator tool you mentioned on your page here: smartcybersecurity.eu/tag/cybersecurity/
While cisa.gov does a good job, it only allows you to create favicons from pictures that are up to 2 MB in size.
After some exploring I found this other tool and I wanted to suggest you show it along that one.
this tool allows you to create favicons from pictures that are up to 5 MB from either JPG, PNG or GIF or even from a gallery!
In hope I helped back,
Libre de virus. www.avast.com