Read indicator incorrect when messages race for time ordering

### Steps to reproduce

1. Party A sends a message and Party B sends a message, supposedly B timestamps its message **before** A's message
2. On A's phone, A's message appears before B's message

### Outcome

#### What did you expect?

B's read indicator ("B has read that message") as seen by A appears on B's message.

#### What happened instead?

Said read indicator appears on A's message, suggesting B hasn't read its own message.

### Your phone model

_No response_

### Operating system version

_No response_

### Application version and app store

1.3.9

### Homeserver

matrix.org

### Will you send logs?

No