Room notifications seem to behave weirdly

### Steps to reproduce

1. Create a username with eg `sm` as the name
2. Join a room
3. Enable room notifications as mentions & keywords (don't set any own config for it)
4. Join the room from another client
5. Type anything with the username in the middle like `tesmt`
6. Notice the notifiaction

### Outcome

#### What did you expect?

Not get notified of all messages that include my username in the middle.

#### What happened instead?

Got notified

### Operating system

Gentoo

### Application version

Element version: 1.11.22 Olm version: 3.2.12

### How did you install the app?

https://packages.gentoo.org/packages/net-im/element-desktop-bin

### Homeserver

pikaviestin.fi, Synapse 1.78.0

### Will you send logs?

Yes