These are URLs with a letter that looks similar to another letter in the same script, but visually distinct.
e.g., “gṃail.com”, “asĸ.com”, “manħattan.edu” (all Latin)

These have mostly been handled by  bug 703750 , but we can’t fully solve it because these letters are allowed in domains. However we do restrict domains that are similar to top 10k domains.

There are a few other things we can do:
- Bug 722022: Find a mechanism to update to top 10K list.
- Bug 847662: Compare URLs against a list of domains in the user's browsing history (in addition to top 10K list)

This is a tracking bug for that effort.