"Jump to unread" remains visible, even though there are no unread messages

### Steps to reproduce

1. Receive a number of new messages so that you will need to scroll to read all of them.
2. Open the room to read messages.

### Outcome

#### What did you expect?
Room opens at the chat position it was left. No "Jump to unread" popop is shown, since the screen begins at the first unread message.
#### What happened instead?
"Jump to unread" popup is shown and does not disappear, unless I close it explicitly. Clicking on it jumps to the first of the batch of messages I've received, which I have already read.

### Your phone model

Galaxy M51

### Operating system version

Android 12

### Application version and app store

1.4.20

### Homeserver

Synapse 1.55.2

### Will you send logs?

Yes

### Are you willing to provide a PR?

No