Some characters get turned into HTML codes when sending message

### Steps to reproduce

1. Switch rich text editor on in Settings -> Labs
2. Send the message `/me -> foo` in a message

```
{
"content": {
"body": "-> foo",
"msgtype": "m.emote"
}
}
```

### Outcome

#### What did you expect?
See `* user -> foo` in the timeline

#### What happened instead?
See `* user -> foo` in the timeline

### Your phone model

_No response_

### Operating system version

_No response_

### Application version and app store

1.5.10 Beta track gplay

### Homeserver

_No response_

### Will you send logs?

No

### Are you willing to provide a PR?

No