"Enable notifications for this session" nominally-respected across restarts, but "Background sync mode" automatically reset to "Optimised for real time" – with the persistent notification or "1 app is active" – and needs to be enabled/toggled/disabled each time to revert

### Steps to reproduce

1. Settings -> Notification -> Background synchronisation -> Background Sync Mode: set to No background sync
2. Settings -> Notification -> Notifications -> Enable notifications for this session: disable
3. (I'm assuming "session" means device as a matrixism)
4. Fully exit out of the app, make sure it's dead
5. Next time it opens the startup will take a while with a throbber and "Importing your data"
6. The persistent "Listening for notifications" notification appears
7. OBSERVE: Settings -> Notification -> Notifications -> Enable notifications for this session: it's "disabled"
8. OBSERVE: Settings -> Notification -> Background synchronisation -> Background Sync Mode: somehow set to "Optimised for real time"
9. toggling "Enable notifications for this session" (and even "... for this account") doesn't kill the persistent notification or change the "Background synchronisation" mode
10. Need to: Settings -> Notification -> Notifications -> Enable notifications for this session: enable (since this undisables the Background Sync Mode button)
11. Need to: Settings -> Notification -> Background synchronisation -> Background Sync Mode: set to No background sync
12. Need to: Settings -> Notification -> Notifications -> Enable notifications for this session: disable

### Outcome

#### What did you expect?
My configuration is preserved.

#### What happened instead?
See above, steps 6-.

### Your phone model

Sony Xperia Z

### Operating system version

9

### Application version and app store

1.6.6 [40106051] (F-fd6a45a3)

### Homeserver

nabijaczleweli.xyz Synapse 1.93.0-1

### Will you send logs?

No (I would've said yes to this but (a) even after enabling the rage shake it doesn't work, (b) "shaking my phone to make something happen" is demeaning bull shit I ideologically refuse to do, and (c) `/rageshake` doesn't work! it does on desktop, why did you remove it? what purpose does this serve?).

### Are you willing to provide a PR?

No