A flag icon is usually for reporting content, use a hash instead

Follow. Hash or, you know, an actual Anchor, arrr matey.

Nice idea Lorenzo!
Yah, I like this to be as an optional filter/option in the selected text format.

The problem I can foresee is training non-technical users to understand the difference of when and when not to enter the hash when creating anchors, and links to the anchors. Technically this is already an issue, but would be exacerbated by the new Hash icon in some ways.

Think of the common use case of creating a Table of Contents with URL fragment links to anchors down the page on a really long page.

Users will need to grok this:

• when you create an anchor you'd click the # icon, and NOT ENTER a # inside the popup.
• when you create a link to an anchor you'd click the 🔗 icon and ENTER a # plus the anchor name inside the popup.

The fix would be to improve the UX in the popup itself, to include the hash sign before the input field, so users get trained not to enter it manually on the anchors.

I really liked the hash idea, but I love both the anchor (seems so obvious it's perfect) and adding the hash to the input. Nice, @jwilson3!

Agree with #3 that it probably needs to be an option to avoid changing existing installs. Maybe just an option to provide a path to an alternative icon file?