Very slow notifications when using ntfy due to Element seemingly asleep

### Steps to reproduce

When using with ntfy for Unified Push notifications send a message to any relevant room that will cause matrix-synapse to issue a notification when Element is not currently active (using Unrestricted battery with all Notifications enabled) then just *wait* (for sometimes minutes).

### Outcome

#### What did you expect?
The notification to occur within a couple of seconds (which all normal "ntfy" notifications are doing).

#### What happened instead?
It can take from a few seconds to a few minutes for the Element Unified Push notification to be announced (unless you "hack" around it).

#### How did you hack around it?
I duplicated the (postgres) 'pushers' row for the upNNNN changing its 'id' and 'pushkey' it to upNNNNX (then restarted matrix-synapse and manually subscribed to upNNNNX in 'ntfy' on the mobile phone).

Now I get the Element notification within two seconds (every time) although of course I also get an ugly upNNNNX notification (and then another one after marking as read).

I can image going further to try and work out how to neaten up this ugly hack - but why should it be needed?

Notifications are ESSENTIAL and Element with 'ntfy' is just hopeless if you need to hack it like this (the same thing occurs with Element-X so I will duplicate this issue there).

### Your phone model

Google Pixel 8.0

### Operating system version

Android 15 (Graphene OS 2025050700)

### Application version and app store

1.6.34 (F-Droid)

### Homeserver

(self hosted)

### Will you send logs?

No

### Are you willing to provide a PR?

No