Error message "Unable to decrypt. MatrixSDKCrypto.DecryptionError" appears randomly in a chat with a single user

### Steps to reproduce

I self-host a dendrite instance (via docker, federation disabled) on a Raspberry Pi 4 (4GB) where there are at the moment only 2 users in total. One user uses element on iOS and randomly gets an error message where it has been impossible to establish the steps to reproduce how to get that error. The error appears randomly when the chat window with the other user is opened or when a message is being typed. It is also difficult to foresee how often the error will happen. Sometimes it can be twice a day, while other times it could be once a week.

The other user – which uses element on an Android device – has never experienced the error described in this issue.

### Outcome

The user using element on iOS expects to write a message but it is instead sometimes and randomly presented with the error as in the following screenshot:


```
** Unable to decrypt: Handlingen kunne ikke udføres.
(MatrixSDKCrypto.DecryptionError fejl 2.) **
```

Element iOS interface is set in English but the iOS system language is Danish.
`Handlingen kunne ikke udføres` could be translated as `The operation couldn't be performed`.
`Fejl` in Danish is `Error`.

Additional information taken from the Element iOS settings that might help:
```
Matrix SDK 0.26.10
Rust Crypto SDK 0.6.0 (Vodozemac 0.3.0)
```

### Your phone model

iPhone 8

### Operating system version

iOS 16.5

### Application version

Element 1.10.12 (20230516163937)

### Homeserver

Dendrite 0.12.0+74dc546

### Will you send logs?

No