How to prevent email address from being suggested when composing email in Gmail

When composing an email to certain addresses in Gmail, it suggests more addresses to add. How can I prevent a specific email address from being suggested?

I can remove the offending email address from all contacts (including "other contacts") and this will prevent the "person" being suggested. However, it will still suggest the "email address" only (from a "non-contact" - when hovering over this email address there is the option to "Add to contacts") - presumably because there are past emails where this email address is included. (I don't want to delete these emails.)

This Google Community thread from 2019/20 is asking the same question, without a solution:

• https://support.google.com/mail/thread/4904445/how-to-disable-suggested-email-recipients?hl=en

Failing that, how can I prevent any email address from being suggested?

I've tried toggling the following "smart" features in Gmail "general" settings, but none seem to affect this "Add email suggestion" feature:

• Smart Compose / Writing suggestions
• Smart Compose personalisation
• Nudges: Suggest emails to reply to
• Smart Reply