GCM connections never last for more than 1 minute. Is this normal?

Describe the bug
It seems microG's GCM is not stable. In my case, it disconnects once every 60 seconds and recovers about 5 seconds later.

The Status' "Connected since x seconds ago" never went beyond 1 minute for me.

Setting different ping intervals doesn't help, either. It seems the "Automatic" option is already setting an interval higher than 1 minute so I might be having a different issue than #1011.

I haven't gotten a logcat yet, but a hint about what kind of log messages to look for is greatly appreciated.

To Reproduce
Steps to reproduce the behavior:

1. Go to microG settings
2. Click on Google Cloud Messaging
3. Check Status
4. The Status would say "Connected since xxx seconds ago", but when it reaches 1 minute, it becomes Disconnected and about 5 seconds later it becomes Connected again.

Expected behavior
Unless this being a normal behavior, the Connected status should stay for long enough, disconnections should not be frequent.

Screenshots
No screenshots for as it's self-explanatory.

System
Android Version: 10
Custom ROM: Havoc GSI 3.8 running on Razer Phone 2 (with arter97 r14)

Additional context
All self-test states are checked so microG is running normally. I'm using NanoDroid, with microG installed systemlessly.

I noticed I'm receiving messages very late (can be as much as 10-15 minutes), unless I put that particular app in the foreground before I set the phone to sleep. Maybe this is related.

Start with the reproduction steps in the issue: observe the GCM status through the one-minute disconnect and collect the requested logcat output. Compare the disconnect and delayed-message behavior to determine whether it is expected or identify the failing connection path; done means the behavior is explained or a concrete fix scope is established.