Internationalized Email Addresses, for example প্রোটন@তৌহিদুর.বাংলা is not supported by Proton Mail. When I type my email address in Proton Mail, it weirdly tells me address is not valid.
Note that popular email service providers such as Gmail supports this.
To Reproduce:
Try to send an email to the email address given above.
I would say that you are seeing things from an English speaking community perspective. IDNs and Internationalized Emails exist for a reason. It’s bad to see everything new as a potential security risk.
It’s not really new. It’s just uncommon and it can be abused to make different spellings that look like English spellings but aren’t.
It’s kind of like goog l e.com vs goog I e .com but on a much larger scale.