For example, this is the entry of Superuser when I opened bookmark html in notepad.
<DT><A HREF="https://superuser.com/" ADD_DATE="1674863395" ICON="data:image/png;base64,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">Super User</A>
As you can see, it's a long-winded string for Icon parameter.
What is this and why does it have to be so long? Can I not shorten this?