Number of recent messages increases with message deletion

### Steps to reproduce

1. Have a conversation with someone to build up a conversation history.
2. Have the other person start deleting messages while you're slightly scrolled up enough to see the "Scroll to most recent messages" icon.
3. Notice each deleted message causes the icon's badge, which shows the number of new recent messages, to increase as if new messages were posted.

### Outcome

#### What did you expect?

Deleted messages shouldn't increase the most recent messages count.

#### What happened instead?

Deleted messages will increase the most recent messages count making it look like new messages are being sent.

### Operating system

Arch Linux

### Application version

Element version: 1.10.1 Olm version: 3.2.8

### How did you install the app?

FlatHub

### Homeserver

matrix.org

### Will you send logs?

No