Unable to decrypt message involving unicode MXID domain

Encrypted messages sent from iOS can't be decrypted by homeservers that are using an unicode domain name.

Unencrypted messages or encrypted messages from other clients to the unicode MXID can be decrypted.

### Steps to reproduce

Steps to reproduce the behavior:
1. Create an encrypted room with an user that uses a MXID which involves unicode character (@i401:xn--vl1a.moe in this case)
2. Send a message
3. Message can't be decrypted

Screenshots

i4-tst in this case is on the iOS-Element client.

### Outcome

#### What did you expect?

Encrypted messages should be decrypted

#### What happened instead?

Message can't be decrypted and re-request encryption keys silently fails.

### Your phone model

iPhoneX

### Operating system version

iOS15.4.1

### Application version

Element version 1.8.14

### Homeserver

matrix.org

### Will you send logs?

No

The report names no source file or test. Start by reproducing the failure with the reported Unicode MXID and trace the iOS encrypted-message key re-request and decryption path, comparing it with unencrypted messages and other clients. Done means encrypted messages decrypt and key requests no longer fail silently for the reported domain.

Written by the indexing model from the issue text.