[BUG] Notifications about upcoming lectures at seemingly random times.

[Leoniepopken]

Describe the bug
A clear and concise description of what the bug is.

I get notified about upcoming lectures at the most random times imaginably:
today I got the notification Übungen zu xyz... in 6 days. A few days ago it said something similar.

Expected behavior
A notification should always be sent shortly before a lecture.

Smartphone (please complete the following information):

• Phone: Samsung Galaxy S 10
• OS version: Android 12
• Language: German

[kunzef]

Hi just wanted to let everyone know that I'm currently working on #1235 and once finished, would with the gained knowledge there, tackle this issue.