Push notifications have inconsistent priority

[robotfishe]

Describe the bug
ShildiChat Next notifications on Android seem to go back and forth between being treated as high-priority notifications alongside other messaging apps and being treated as normal-priority. When they come through as high-priority - which I would consider the expected behaviour - they are pushed to the top of the notification shade and separated from other notifications (see first screenshot). Other times, they end up amongst other lower-priority notifications like emails and task reminders (see second screenshot). There doesn't seem to be any pattern or logic to which category they end up in - the two screenshots below are from the same person/conversation, received about 2 minutes apart.

To Reproduce
Steps to reproduce the behavior:
Receive a message with the app not open in the foreground.

Expected behavior
Standard behaviour on Android is for instant messaging apps to have high priority when handed off to the notification API.

Screenshots

Smartphone (please complete the following information):

• Device: Google Pixel Fold
• OS: Android 15

Additional context

• App version: 0.9.0 (9900)
• Store: Google Play
• Homeserver: self-hosted (Synapse)
• Related experimental/labs settings: None enabled
• Logs have been submitted using the app's built-in bug report (/"rageshake") mechanism: no

Upstream relevance

• Does this issue exist in Element X Android?
  Actually my experience with Element X is that it never puts notifications in the high-priority space, so SchildiChat seems to be doing better sometimes but not always.