Authenticity of own messages cannot be guaranteed

### Description


### Steps to reproduce

- lets have multiple ecrypted and properly cross-signed devices
- all except for mobile with Element Android are offline
- send messages from Element Android in the evening
- look at those own messages in the morning on home PC - grey shields next to messages sent from Element Android previous evening, cache cleared - no change
- look at those own messages in the morning on work PC - no problem, no grey shield, same Element Web page

There shoudn't be any grey shields on home PC.

When a new Element Web session is created, all existing messages within all e2e rooms, have that error message with grey shield. New messages are ok, no grey shield is shown.


### Version information

- **Platform**: web
- **Browser**: Firefox 89b7 on both PC
- **OS**: Windows
- **URL**: self hosted Element Web 1.7.26