Error in sender address transformation

[RandomGuy28]

Prerequisites

• I have searched open and closed issues to make sure that the bug has not yet been reported.

Bug report

Describe the bug
When you receive an email from someone whose name contains Korean Hangul characters, the "(a)" in the transformed sender's address disappear. For example, john(a)wick.com would become johnwick.com.

I only tested this with Korean characters, but I expect this to apply to all 2-byte characters, like Japanese and Chinese.

Expected behavior
The “(a)” in the address should not disappear, regardless of the sender's name.

Screenshots

Environment (If applicable):

• OS: Windows
• Browser: Brave
• Version: 1.66.115
• Email Provider: Proton Mail