URL previews are visible momentarily in encrypted rooms

### Steps to reproduce

1. URL previews have been enabled in the client
2. A new message that has a URL in it arrives in an encrypted room
3. A URL preview is shown below the message
4. Shortly after (possibly only after I scroll) the URL preview disappears

### Outcome

#### What did you expect?

As the room is encrypted, I expected that a URL preview would not appear at all.

#### What happened instead?

A URL preview was briefly shown. This, in my understanding, means that the URL was sent in clear to the home server for the purpose of generating a URL preview.

### Your phone model

iPhone 11 Pro Max

### Operating system version

iOS 16.1

### Application version

Element 1.9.9 (20221018161714)

### Homeserver

Synapse 1.69.0

### Will you send logs?

No