Element (occasionally) repeatedly spams `/sync`

### Steps to reproduce

1. Use app.element.io
2. Create a message or two
3. Sit back and observe the developer tools

### Outcome

#### What did you expect?
To only request `/sync` upon when
#### What happened instead?
All these elements share the same `since` parameter.
About 20,000 requests have been made in a matter of 30 seconds

I suspect this is an synapse issue, where long polling is incorrect.

### Operating system

Arch Linux

### Browser information

Chromium Version 112.0.5615.165

### URL for webapp

localhost

### Application version

Element version: 1.11.26 Olm version: 3.2.12

### Homeserver

Synapse 1.82.0

### Will you send logs?

Yes