Hi there,
Thats WP sanitizing the output – it don’t like inline SVGs within that field so it strips it. You would have to use an <img>
tag instead. Or build your own Footer Bar with a Block Element and the GB Blocks Plugin which will support inline SVGs.
Alternative you can use a HTML Symbol like this for the Heart:
<span class="heart">❤</span>
Reference to HTML Symbols: https://www.toptal.com/designers/htmlarrows/symbols/heavy-black-heart/
If the device has Emojis it will use them, if not it will fallback to the built in heart icon in the browser.
Then a little CSS for color:
.heart {
color: #f00;
}