Composer text decoration buttons can break

### Description

Somehow the strikethrough button does not work first click and then messes up when you try again. Ctrl+Z reverts to the correct/wanted state that was never visible (but possibly there in the background).

### Steps to reproduce

1. have the following message
```
- 2
- 4
- 9
- 9.5
- 14
- 16
- 86
```

2. edit and highlight `86`
3. click on strikethrough button
4. nothing happens, click again
```
- 2
- 4
- 9
- 9.5
- 14
- 16
- el>86
```

This reproduces solidly for me

Logs being sent: no

### Version information

- **Platform**: desktop

For the desktop app:

- **OS**: Arch
- **Version**: aur/element-desktop-nightly-bin 2021060101-1