Simply FYI: The "Notes" section of the Zotero documentation still references TinyMCE.
While reviewing the documentation for the Notes section on the Zotero.org documentation page, I noticed that this page hasn't been updated since 2017. It's no longer accurate as of the Zotero 6+ releases. At present, it states the following.
EDIT 1 (Jun 21, 2022 11:02 AM CT): Earlier today, I realized that users can request access to edit the Zotero documentation via a separate Wiki account. I have created such an account and requested access.
I'm pointing it out just to be helpful."Notes are searchable and support HTML formatting (Zotero uses the TinyMCE HTML editor for note editing)."
EDIT 1 (Jun 21, 2022 11:02 AM CT): Earlier today, I realized that users can request access to edit the Zotero documentation via a separate Wiki account. I have created such an account and requested access.