Can't decrypt more than two messages in a room

### Steps to reproduce

1. Go to `!kLmEuMmrBeOizxKsjm:matrix.org` or `!RqphPmfqRYPWcDpkqi:matrix.org`

### Outcome

#### What did you expect?
Backlog of messages

#### What happened instead?
See this error for messages before 10:29 (BST) Wednesday:


This has been happening since yesterday morning on different versions of develop. The previous message was on Tuesday and is not a thread.

Refreshing or navigating away+back fixes the problem until I navigate back to the room some time later.

I'm also seeing new message notifications for this room, but I don't believe that there is any discussion/events happening there.

### Operating system

Arch Linux (64-bit)

### Browser information

Chromium 100.0.4896.75 (Official Build)

### URL for webapp

develop.element.io

### Application version

_No response_

### Homeserver

Element version: 691b8d5c38ee-react-763edb7ab930-js-e133005b444b Olm version: 3.2.8

### Will you send logs?

Yes