RR failing to use profile data

### Steps to reproduce

1. Send a message into a room
2. Later, foreground the app
3. Get a read receipt (RR) from a user in that room
4. Panic that the RR has an default avatar of K - but there are no users whose name begins with a K in the room
5. Hoverover it to see what's going on

6. Realise that the RR is just not picking up either the displayname nor avatar of the user, hence extreme confusion.

### Outcome

#### What did you expect?

Uphold the profile.

#### What happened instead?

Profile is ignored / missing. Sounds similar to other bugs where profiles go missing: https://github.com/element-hq/element-web/issues/31300 and https://github.com/element-hq/element-web/issues/7417 (or https://github.com/element-hq/element-web/issues/21034)

### Operating system

macOS

### Browser information

Chrome

### URL for webapp

develop

### Application version

Element version: 1.12.8 Crypto version: Rust SDK 0.16.0 (95b5e83), Vodozemac 0.9.0

### Homeserver

matrix.org

### Will you send logs?

No