Notes: mention notification emails show raw HTML around tagged usernames in some email clients (e.g. Apple Mail); renders correctly in Gmail #82096

Description

Mention notification emails render inconsistently across email clients:

• Gmail: tagged usernames render as expected (styled inline links, no visible markup).
• Apple Mail: the HTML wrapping around tagged usernames is visible as raw markup in the email body.

Steps to reproduce

1. Add a Note on a post and mention a user (@someuser).
2. Save the note so the notification email fires.
3. View the received notification email in Apple Mail
4. View the same email in Gmail (web)

Expected

Mentions render as plain text or styled inline links (no raw markup) in every mail client, regardless of whether the client renders HTML or falls back to plain text.

Actual

The HTML wrapping around tagged usernames is exposed in some clients (screenshot from reporter linked below).

Environment

• WordPress 7.1 / Gutenberg 23.8
• Reproduces in Apple Mail; not observed in Gmail (web).