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.
Did you bother to contact their customer support asking if they plan to add this feature?
In my biased opinion, I would imagine Gmail would want to use you and your emails for every ounce of data they can squeeze out of it. However proton is a paid service who doesn’t sell your data, with much less Human Resources than google, therefore less language support. They add things as fast as they can get around to them. If you inquire they might be more apt to add the support if they have someone on staff that can do it.
The EU should mandate support for its native alphabets (probably via Unicode) for IT service providers that provide services in the EU.
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.