scrolling with the scroll bar jumps all over

### Steps to reproduce

in any room with history, trying to scroll with the scrollbar will like jump down as more things load making it near impossible to keep your place when reading a chat log

### Outcome

#### the view doesn't move as new content loads
in discord's implementation, it's because they have placeholder content to hold the view in place while new messages load
#### it jumps down constantly

### Operating system

any / all

### Browser information

tested webkkit, gecko, chromium

### URL for webapp

app.element.io

### Application version

Element version: 1.11.5 Olm version: 3.2.12

### Homeserver

the-apothecary.club

### Will you send logs?

Yes