Android notification not working

[InfinityLoop1308]

• This is not a feature request (existing functionality does not work, not missing functionality).
  I will request features on forum or via support.
• I've searched and did not find a similar issue.

Bug in mobile app

Describe the bug
Android notification not working. Battery optimization is disabled. Can not receive any notifications once you close the app.
When reopen the app, it shows "offline" and reconnects in a few seconds.

To Reproduce
Steps to reproduce the behavior:

1. Download, install, login
2. close the app
3. no notifications, not any.

Expected behavior
Notification works properly

Screenshots
If applicable, add screenshots to help explain your problem.

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: LineageOS 18.1
• Version 3.98.15

Additional context
This bug has existed for a long time.
I have submitted this issue in January(#3796), and make a fix(#3801). After that, I waited for months for the merge. However, they are all closed for no reason.
I really think Tutanota is an excellent app, but this bug make it totally unusable. I believe I am not the only one who have this problem - there must be others encountered this problem and just leave Tutanota silently.
To make Tutanota better, please, don't ignore this issue and pretend as it never occurs. I am willing to provide any information needed ASAP.