Fallback notifications shown with "error sending request for url" error

### Steps to reproduce

1. Where are you starting? What can you see?

I get inconsistent notifications on my mobile device: some show the text, but I still get some that show the fallback notification. I even sometimes get notifications that are completely blank. I heard the WorkManager feature might fix this, so enabled it, which did help. However, I'm still getting fallback notifications.

From the Developer menu, I can see they're "Unable to resolve event: Unknown error: error sending request for url (...)". Clicking on them however shows the correct message in the room. So at least after-the-fact they seem to be correct

### Outcome

#### What did you expect?

I expected to get notifications with the message text consistently.

#### What happened instead?

I'm getting a mixture of fallback notifications and even occasionally some entirely blank ones.

### Your phone model

Pixel 7

### Operating system version

Android 16

### Application version and app store

25.10.1

### Homeserver

mozilla.org

### Will you send logs?

Yes

### Are you willing to provide a PR?

No