Leaving or posting into a specific room results into an error

This issue has been migrated from [#16122](https://github.com/matrix-org/synapse/issues/16122).

---

### Description

When leaving or posting into one specific room Synapse returns an error.

Seems like an invalid state for this specific room / contact.

The room is on another server which does not run synapse but dendrite.

### Steps to reproduce

- Not sure if this is reproducable.

### Homeserver

Private one

### Synapse Version

1.90.0

### Installation Method

Docker (matrixdotorg/synapse)

### Database

PostgreSQL single server 15.0-alpine docker

### Workers

Single process

### Platform

Linux with a Kubernetes cluster

### Configuration

_No response_

### Relevant log output

```shell
2023-08-16 14:00:29,996 - synapse.http.server - 134 - ERROR - POST-60649 - Failed handle request via 'RoomMembershipRestServlet':